I must lead a charmed life. The only firearm I own that I wouldn't rely on at the moment is a new Dan Wesson, which had a number of failures to feed its first time out. These appear to be magazine related. When I swapped out the DW magazines for Wilson Combats, the problem vanished.
I have a Springfield Armory that doesn't like wadcutters. Since I don't carry wadcutters, this isn't really a problem.
The firearm on my hip at this moment is a Series 80 Colt's Commander I bought used from DownbyFive, who was (may well still be) a member here. As a matter of fact, it was he who supplied those Wilson Combat mags. Truth be told, I do love this pistol.
As for a firearm that will fire in spite of gunk, rust, crap, dirt, that would be the SKS, which was giving us decent groups in spite of its relatively abused condition.