Depending on where I'm the world you are, there is nothing that can be done. I at least know where I live in the US, I could put a sticker for something like l337x or Ru Tracker and the worst thing that could happen (without any links) is that someone keys off the stickers.

Though I feel like I'd be more likely to be pressured by a police officer to remove the stickers for some bullshit made-up law that those stickers are in fact illegal (despite it only being a logo/name of the website).

Also, just having a sticker might attract attention, but the people whose attention it tracks would need actual proof of anything wrong going on before they actually make a move.