Well, let's say that a scammer (of art) made an alt for scamming. He stole HQ art, and then sell it on this alt. Then he send all the TC to his main account.

My question is, if this happen, a market squad will ban this alt or his main account? I mean a anybody can look to his old trades no?

If a Market Squad member gets involved, they can check IP's. If this alternate account user is stealing art via this alternate account and then selling it via his main, both would get banned.

No no no, i mean, he stole art (doesn't mean on what account) and sell it on this alt. Then all the tc he made will be send to his main. What account will be ban?

If that is the case, they are still both able to be banned. It is texture theft none the less, which is a bannable offence.

Well, let's say it like this: You make an alt only for scamming art. You stole it, sell it on this alt, make some tc (i mean like over 200k or more) and then from this alt all tc are send to the main. A market squad in this case can check the alt account trade history and see to which user tc were send. But he can't ban the main account because the scammer can say something like on his main account: He bought art from me or he can say i bought his tc. Then the scammer needs proofs no?

The scammer would need valid proof to back up whatever they were saying. In the case of buying tc, they would need a picture of the transaction of USD (probably on paypal I would assume), or they would need evidence that you actually bought art / a set from them, such as screenshots of entire pm's and pm histories.

Oh now it is clear for me. thx.

It's not exactly like that. As a staff member, I have the power to view everything you've ever traded, which is known as your transaction history, and every account that shares your general location, which is known as your IP. As an example, I know that you so happen to have created an alt named azzefirr around August 3rd of 2013, and used it yesterday around the forums. You can't send illegally acquired tc from one account to another and just plead ignorance, because we have ways of telling exactly how you got that money.

This account isn't mine xD, that name of my main account is from a friend steam account and i used it. And my friend used the same name for his account. And now he didn't played toribash for a while and he gave me his account, and i rarely use it.

What do you mean with account sharing??