not all the bugs are bad for the soil, but you need to understeand if those are coming (and maybe living) in your soil or not and how many of them are (if too much think about drowning them). in the end, we're playing with living stuff so it's normal sharing some enviroment with other living beings. but is not a big deal: i got always little gnats which doesn't affect the plant at all since are eating the leafs that fell naturally :))