looks like snail/slug to me and its slimy trail.
watch out for small 1/2inch snails slugs, i found really small shits this year!
Looks more like overspray than anything. A slime trail would be an actual trail, from one place to another, these are simply dots. If you got a picture of it among the rest of the leaves it would be easier to get some context but I highly doubt its snails/slugs.
How have you been dealing with the gnats?
check the middle pic, there is some white looking worm things. pic isnt great but it looks like a live worm/slug
the damage does look thripy, but those worms seem a bit big to be thrip larva, but who knows, its not a great pic, either way spinosad will help.