Well the best thing to do is buy from a known good reseller like Liionwholesale.com - his support is phenomenal, and tests every batch that he gets in. I always will prefer buying cells from him based on availability and price (reasonable that is). imrbatteries.com is also good, personally don't know if their support is as good though.

But as mentioned before, you could be at as much risk buying a rewrap or branded cell - dunno if the branded cell is a fake or recycled as well.