Teemo really is the best troll character, making him amazing for solo queue.
No matter what, he will always have a "place" with his Shroom/wards and annoyance, forcing the other team to buy Oracles and punishing bush facechecks, and even if you do have Oracle's the other team already knows you are there.
Also the best "stealther" now too ironically since the changes since he can just sit there and wait a bit or even escape from detection if he gets 2 secs in shrubbery, plus he is beastly vs any ADC user who is unlucky enough to find him without help. I agree he doesn't add much to teamfights, but it's not like you can just ignore all the aforementioned as if it doesn't matter.
"Cute" opportunist characters are just considered annoying by a lot of people I guess.