Maybe my expectations are too low, but I never assume anyone will reply or hold anything for me, so I don't get very annoyed or take it very personally. If I send a message about a game and don't get a reply, I assume either they never saw it, saw it and just didn't care, thought I was too low, sold it already, or just got busy and meant to but never responded. This isn't because I hate everyone, I just don't want to stress myself out and rearrange my life over something that's supposed to RELIEVE my stress and provide me with some fun distraction.
If we do work out a deal, I try to keep it local because I always assume that I'll get there and the game will be in worse shape, no keys, gone already, or some other catch.
I really try and not to message people about games unless (1) I'm serious and ready/have time to go get it if they say yes, and (2) have discussed with the wife and have cash ready to go. This probably limits me on some games but I find it way less stressful to buy games when the stars align and not sweat the ones that "get away".
For every deal I've "lost" I've found a great one down the road, and let's be honest, I love pinball (and arcades) but this is a hobby and some fun games...there are people with actual problems in the world other than someone ignoring their message about a $2,000 toy .