Some sellers like to tout their feedback numbers like it means something when it comes to them in particular, but in actuality it means little. In some cases one can google a seller name and maybe come up with some interesting information, like how they conduct themselves on internet forums. A seemingly decent seller in feedback may prove themself to be an ass who is an emparrasment to the bisiness and has been banned from many on-line communities. A little research may make you not want to do business with them if they were the only seller on the planet...
And yes, you have to look at the nevatives as well. The best is if there is NO negatives at all.