Wash trading is where someone activates a bot to generate fake trading volume on a token in an attempt to get people to buy the token, pump the price before quickly selling, or rugging them.

Such pools are dangerous and often unprofitable to deposit into because:

1. The bots are programmed to performs swaps through a really low fee pool and not yours.
2. You will only get a very small amount of real trades, thus you will not earn enough in fees to offset losses
3. The token could dump at any second and you would suffer from near immediate and catastrophic losses.