I'm confused here! What good does it do to check their feedback after they're a buyer? By then we're stuck with them!!
I only check feedback of winning bidders in spurts but it can be useful. If a buyer has a record of slow or non payment or other problems you can give them "special" handling like sending follow up notices very quickly or other little things which may make getting paid more likely.
Only a very few of buyers are total flakes, if a buyer has a couple of non-payment negs and 50 positives it indicates they do pay for some things and I'll do what I can to make sure I'm one of the sellers who gets paid.
I never look at feedback of current bidders, for I see no point as it's just as likely they will not be the winning bidder. If I was selling high value scam prone items I might be checking at least for obvious deadbeats.

"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915
- answering Trolls is voluntary, my policy is not to participate.

"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915
- answering Trolls is voluntary, my policy is not to participate.