I posted this question on CSI's LinkedIn group:

One of my clients, a building product manufacturer, calls architects during bidding to ask them to accept his framing accessory as a substitution. (He gets their names from a subscription service of jobs being bid.) When I said that Instructions to Bidders typically states that architect consider substitutions only if requested by a bidder, the manufacturer said that many architects don't abide by their own documents and he has a high rate of success at changing the specs. Now he wants my help with calls.

What would you say to this manufacturer if he told you his strategy? Should a manufacturer treat specs as inviolate or accept the realities of the marketplace?

Here is the gist of the feedback I got from CSI members. As a group, they want manufacturers to know and follow the instructions to bidders as published in the bidding documents. CSI members may not be representative of the industry as a whole, but it is dangerous to ignore them:

Tell him "No, it's not right". Just because he breaks the rules does not mean you have to. There is a possibility that you will loose this client, but doing the right thing never fails. I have witnessed this principal to be true many many times. I understand that sometimes the rules must be broken, but from my perspective, this is not one of those times.
I would absolutely tell the manufacturer "no." If bidding documents say no substitutions or approved manufacturers only, then we should abide by them. I don't accept any calls from manufacturers during bidding as any information would give them an unfair advantage in bidding. I refer them back to the General Contractor or CM.
I would stick to your specs as the product manufacturer should be looking to get into your own office MasterSpec for future projects and not just for the "Now" project.
Manufacturers who market by playing outside of the rules or riding the fence can develop a reputation with the specifying community that is less favorable. It is the merit of the products and the value brought by good support of the products, that really wins, in my opinion.
I would say that in that situation, the manufacturer needs to spend his efforts to convince the architect to include his product in future projects rather than the one out to bid.

...the design professional is the one who's on the hook. If something is designed in, added by addendum, or approved after award of contract, it makes no difference; the person who certifies the documents is responsible. That alone makes me wonder why architects often appear eager to approve anything that comes in the door. Note that I didn't say design professionals in general. Neither engineers nor interior designers I know show little inclination to approve anything other than what they chose, even in public sector work.
I often see that we Architects and Specifiers do not follow what we write or preach. We do allow substitutions be submitted without backup materials and often it is left to us to research and analyze the substitutions. Having said that...we often allow substitution during bidding process for value engineering, but if considered, we still request a formal Substitution for formal review.
As a manufacturer's rep for a line that hasn't had a lot of presence in my territory, there is not a lot of consistency on how to approach substitutions.. .At the end of the day I recognize it's persistence, follow through and building a proven track record in my market.
Maybe it's the backwater I work in, but local reps generally follow the rules, and the new ones have been pretty good at calling to discuss their wares before applying for prior approval or substitution.
The point of having the substitution come through a primer bidder is so that the archtiect doesn't waste time approving products that no one wants to use. And, the manufacturer/subcontractor needs to know what the rules actually are for projects.
Rules is rules, but the reality is, we often make exceptions. If one of my go-to guys calls me, I'll listen. They earned that status by helping me do my job, and I will listen to their advice at any time. They will understand if there is some reason I can't do anything for a specific projects.
Our market tends not to have very many manufacturers who try to bend the rules. Our reps do present their products to us for prior approval to put in our specs for projects. It's only once in a half year or so that I get phone calls or letters asking to bend the rules and they are mostly from outside our market area.
I am in belief that bidding should be done by the process. To that end I will share a story. Years ago I put a project out to bid. The hardware schedule specified products, and acceptable manufacturers. Further, I noted that no other products are acceptable without preapproval by the architect (me), and such request for substitution must be received 7 days prior to bid. So, the contractor submitted the hardware schedule submittal with non-approved products. I sent the submittal back with a statement, these products are not acceptable refer to Section 08700 (the hardware section). Contractor responded that they did not understand. You need to request a substitution. More ??????? from the contractor.
Finally, I issued a statement that the products were not allowed under the terms of the specification section. Should the hardware supplier wish request that these products be used they must request a substitution, and I would have to see the cost back to the owner for this substitution. The contractor said that he could put together the data needed for a substitution review, but that the cost savings was already in the bid price. I responded no it is NOT. The bid price reflects the specified products. Your request for substitution will have to be a cost back to the owner. Guess what I got the specified products. This required me to educate my owner and I had to hold firm in the face of an frustrated, and irritated contractor. If we as the architects, perform lazy, the contractor will seize the opportunity. When that happens, the good products reps get chewed up. I do not want our trusted advisors chewed-up.
I feel like my company is on the same page as most posted here, we do not let manufactures submit for substitutions, it must be the bidding contractor. Buy in is critical, why would a specifier allow a product that won't be bid, it weakens your spec. manufactures are trying to show traction to the corp levels, but in reality if the product doesn't get used everyone just wasted time and money. The other way for contractors/manufactures to do this is actually use the substitution listing form at time of bid, have the contractor bid what is specified and then show a substitution with the alternate product and cost difference. This would prove much more to the owner reviewing bids.

Here is my own answer to the question:

Thanks, everyone, for the thoughtful answers to my questions. I spoke with my client today and recommended against his initiation of substitutions during bidding. I explained it to him this way:

"If you approach the architect during bidding, you might get named in an addendum, but that will not help your long term cause. Bidding is a rushed, chaotic process, and most of the team that put together the contract documents will have moved on to other projects as soon as the job is put out to bid. This means that most substitution requests are reviewed by just one or two members of the project team. They might say 'yes', but that information does not become part of the institutional memory of the firm. Instead, I recommend working with the office so they understand the benefits of the product and you get buy-in from the project architects, draftsmen, specifier, engineer, cost estimator, and other members of the team. Otherwise, they will simply fall back onto old habits, cut and paste old details, reuse existing spec masters, and you will have to fight for another substitution on the next project."

I suggested a sales-oriented approach of working with sub-contractors to submit substitutions after contracts are issued. This works to my client's advantage due to the reduced labor associated with his product.

In tandem, I recommended a business-development goal of working with architects to show how to bring their standard details and spec masters into compliance with best industry practices.

One of my mentors was a forensic engineer. He told me that most of the product failures he had investigated were substitutions that were rushed through without adequate research, coordination, or documentation.