"Unreliable" philosophers

An untenured philosopher writes:

I was wondering if I could solicit an opinion from you and/or your readers.

In my short career thus far, I have encountered a surprising number of philosophers who are "unreliable," one might say. I am not even referring to dubious behavior from journals. I'm talking about individuals who agree to read a draft, and then never do. I'm talking about carefully crafted emails being ignored. I'm talking about people who say they will recommend or campaign for you heartily, but then become coy when it matters. This is not just with senior faculty--I've been treated this way by folks at my own rank. (I don't believe I'm prone to offend people...)

So one question is whether such behavior is generally tolerated/accepted, as part of the culture of the discipline.

But more importantly, how can one respond to someone non-responsive?

Since I am at my most professionally vulnerable stage, I can hardly afford to upset anyone. The main alternatives, it seems, are to sound whining or annoying--or to just keep quiet. None of these seem very good options.

I am inclined to think "just keep quiet" is the only option--that, and make a note about who is reliable and who isn't.  One can't generally force people to honor their representations or to be responsive, even when an e-mail has been "carefully crafted."  Of course, if the philosopher is someone with whom you have a substantial relationship (say, a dissertation adviser, a longtime mentor, etc.), then reminders would be appropriate.  What do readers think? Signed comments preferred, but all comments must include a valid e-mail address, which will not appear.