One meta belief I have, is that I think "on the face pursuing idealistic objective A, but actually being tilted toward selfish objective B" is better than "openly pursuing objective B".

Many seem to believe the opposite, typically saying something like "at least the latter is honest".

I feel like what this misses, is that maintaining the face of pursuing idealistic objective A, and using A to coordinate a large coalition, is a pretty big speed bump against attempts to pursue B too brazenly. When "the mask comes off", things actually become much worse, and strategies that pursue B at high costs to other values (including A, and also often general human decency) become unlocked.

Are there any good arguments against this intuition I have? (Whether generalized, or about specific situations)

Superficially pursuing A while actually tilited toward B creates an unethical informational asymmetry between 2 parties, and can lead to far greater exploitation and hidden conflicts of interest. It also artifically limits the surface area of potential solutions to objective A to those that must also include B