You said it

I would never place a bid for $9.99 myself.

Sure the shill accidentally overbids sometimes
Ive seen many such overbids 'cancelled' by the seller also.

When sellers have repeated patterns of this occurring, as was the case that originally sparked the discussion, I get suspicious.

I won an auction last night from some seller called mrnjchips. I got bid up $70odd on it. Anything can happen I still got a steal, you and I both know that