[mgraczyk]

Almost all limit order books required posting the assets on the book and take a fee on trades. You can read off the amount paid to generate the fictional market cap and judge for yourself if it's likely to be fake activity. For thinly traded books with low liquidity, it's cheap. For thick books with high volume, it's expensive.

Also exchanges that are not participating in scams, actively or passively, will attempt to detect wash trading and stop it.