My experience only; I've seen the FAA look the other way, but my examples have been with Captains not wanting to accept aircraft that there not comfortable with, and the MEL permitting the flight and operation with the so called system INOP. Both examples were low weather, winter/icing, and contaminated rwys, along with multiple other things going on. Capt. Pled the 5th (refused aircraft) along with me, I supported his decision, and we got paperwork over it. Capt went rounds with Union, and both contacted the FAA. The Fed's basically said they don't deal with company displine, which I thought was B.S., and won't even look in to the matter.

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