Hmm sometimes these days I often start posts with something like "I'm not sure it's a good idea to sell this..." - and sometimes it's not hyperbole to amp up a sale thread, it's genuine uncertainty. BUT in any coms with perspective buyers I would repeat my uncertainty and if I changed my mind about selling something it's not because the selling isn't really really aware that I'm conflicted about selling item X.
The other reason I might withdraw something is that if there's a chain going on... like with house sales. I was thinking of selling my G&L L1000 this week to fund a PreEB Stingray... say I put the L1000 on sale, someone enquired, I would have made them aware of the chain and then if the 'ray sold before the L1000 sale went through they would have known I might pull out of the whole thing.
Kinda annoying, I get that, but the key I think is communication and letting the other party know the circumstances where you might pull out. To my mind it's my item, and until money has changed hands there's nothing forcing me to sell it.
In a way, if I get this with something I'm buying it's sometimes not the worst thing, if the bass is any good then probably the owner doesn't really want to sell it! I get it's annoying, but unless it's some kind of unobtanium its just a bass guitar, and usually from a maker who still makes things