It is difficult to determine whether or not to raise a concern when a client is requesting you add or remove a feature that could negatively impact their users. You have to pick your battles carefully when deciding where to stand your ground because, as you mentioned, the client signs the check.

Before you say anything to the client, you first need to determine the impact their request will have on the core user base. If the request will cause problems for only a small portion of their users, I would raise the concern, but not push too hard if the client disagrees. However, if the request negatively impacts their core users, I would raise the concern and try to stand as firm as possible on the issue.

The client is paying you for expertise, and you owe it to them to try and prevent them from making a bad decision. You have to make them see that you are standing firm because you care about their business and want to see it succeed. Provided you can tactfully make your case, your client will respect your point of view, even if they decide not to heed your advice.

Really, what do you say to clients who don’t seem to care about their users? I work in the consulting business, we’re paid to consult our clients. Too often, they just tell us how it should be and we submit because they’re paying us. How do you say to a client “look, you paid us to advise you, not to let you continue your cycle of bad ideas. let us do our jobs.”?