As a potential buyer and infrequent seller, perhaps I sometimes correspond too much. A Nitto rack or some other jewel, its rare that there are crickets on the other end. Heck, at least crickets make noise! But I never thought of Eric's example, and Ken Y hit the nail on the head. If I sit back and think a bit about whether I should purchase something, even if I decide not to go through with a transaction, I do let the other party know my choice. And there will be more folks in line for the item. I even do the same with Craigslist ads cuz it is a real PITA for people to flake out.
Just don't let someone know, hey, if you ever want to sell that bike let me know. I've done that a few times over the years and end up with the f/f or bike, but you know what, I've been happy about the purchase even though I had to choke a little bit on the transaction. All good as these items can find a new home sometimes.
Mike SLO CA