Whats the way to proof other users that bugbelt which i bought many years ago on internet auction is permed? Since they dont believe in clash tests, is there any other way to proof it ?

You cant possibly know that its perm. You might think it is though but you cant know.

Can good clash test prove that bb is perm ?

Cant prove, but it can prove that it is not a commonly duped ID.

It doesn't even matter. Unless you have a list of history that everyone else on it had previously maintained and will vouch, you can't really prove it. And neither can they. No action will be taken either way and the only trading consequences will be from a popularity contest if people decide to take so and so's word and avoid trading with you.

The accused will be asked, "did you sell a non-perm as perm? The accused will say, "No." End of story. He said she said.

sell it as perm like everyone else does

Wait to see if they poof

I trust u

Toss it at me and I'll put it thru 1000 Baal runs. If it doesn't poof, it's perm

The only to 100 proof is perm, is if you bugged it yourself when it was possible
Even with a history there's no guarantee it wasn't duped somewhere in the chain