You've summed up my thoughts exactly. At what point though does it all become pointless guesswork? Yes if there are bids already you often see someone, for reasons I can't fathom, chiping away with ever increasing bids just to ensure they are on top. Until someone else bids higher. They often stop at nice round numbers so you can get an edge by not doing the same.
Does the presence of a bid encourage more people to bid than it discourages those who think an item with a bid is not going to be snapped up as a bargain? Who knows.
At the end of the auction after everyone has bid the item gets sold to the highest bidder regardless of the bidding shenanigans that has gone on. The last second sniper will still always win the item IF they bid more than you were prepared to. If you lose the bidding because you tried to be clever and wound up having bid less than you were willing to pay then you only have yourself to blame.
It's all psychology. If you see an item without bids, that's where you want to keep it. You can be assured that there are others watching it, and what your goal is to have a last second showdown, everyone puts in their maximums, and the one with the highest wins.
Because in that case, the item will likely go for a realistic price.
If you put in a bid early, there is guaranteed to be a blockhead around who'll just keep bidding until he reaches your maximum and comes out on top. The way he's thinking is "well this guy put in $80, it sure as hell is worth $85 for me". The end of this is that the item is bid up to a ridiculous price, where it's quite far from a bargain, and you sure as hell don't want it for that price.
List out the auctions ending today. The ones you're interested in are the ones that are, at this moment, well below your pre-decided bidding price. Then, bid that price on them at the last moment. This way you're protecting yourself from your own endocrine system (which WILL drive you into doing something stupid if you let it), and also minimizing the damage from the stupidity of others.