I have recently become aware of legal (it seems) but highly dubious techniques by which sellers are creating feedback for themselves to look like trustworthy members of the community.
There are even listings on eBay selling the technique.
It is very simple. The sellers are merely buying a large number of 1 cent/penny listings for meaningless products for which they pay and then give and receive positive feedback.
A tip when considering a seller - Look at their selling activity (their feedback from buyers) as their performance as a buyer is not necessarily relevant.
If you see a seller with a large amount of buying activity in a very short time period they have probably been doing the above.
Also, if a deal seems to good to be true, it probably is!
Happy and safe buying!