It's clear that these bots hurt poker players, which is why online poker companies work so hard to get rid of them. But they're not actually breaking the law. They're just being evil, which isn't in and of itself illegal.
However, bots are not so sophisticated that they cannot be spotted, even by non-expert players. Some telltale signs can include: Repeated use of identical bet-sizing (although some human players also play in this way) Repeated use of uncommon lines like check-raising rivers or 5-bet folding pre-flop.