(Yeah, I'm jumping in again when someone directed a comment to someone else)
When I'm bidding, I look at quantity of offers. If there are 20 of one item and 2 of another, I'm probably going to bid on the one with 2 first. I still have a pretty good chance on gettimg the ither one another day.
Personally, a lot of my offers are things I received in bulk swaps that I didn't have room for this year, so I only have 1 or 2 available. Or I only have a couple bagged right now & want to see how much interest there is before bagging up a bunch more. Last time I had to bag some during the swap & I'd like to save myself the hassle this go round.