Like any auction, I'm sure Yahoo Japan
has it's share of shady happenings. 
As an overseas bidder who does not read
japanese, I always worry a little about
the authenticity of the item. But I also
have someone translate the description for
me before I bid. Still, I don't know why,
that uneasy feeling doesn't go away until
I receive the item.

I haven't seen any bids dissapear, at least
not the ones I've been involved in. Yahoo
Japan does do one thing that ebay does not,
it posts the bid history and amounts while
the auction is still open. Makes me wonder
why ebay doesn't do this as well. 

The bidless cels most likely just come
down to popularity of the series. Or
maybe they have a lot of similar cels
on dealer sites/stores in Japan. In any
case, if you bid Yahoo Japan, I suggest
you have someone translate the description
and possibly have a knowledgable friend check
it out as well. Any auction can have frauds, 
just check out the lain321 thread!