I have specifically warning you to stop placing signs joking around other players building styles. Yes, was directly to you, not in public chat. Since don't break any rule, each player can play as they want or know how. And if the intentions are to help other players, give suggestions to them on how to make better. Only saying "PROBLEM" don't help in many times, but it's a indication (despite the fact many players don't see competitors signs, as explained
here
).
It's a known fact your lack of respect with other players and server rules... But I won't take that as a acceptable behaviour, mocking signs, explosions or whatelse your brain come up to. I'll repeat my words used some years ago to other player: "Respect to be respected". Because OpenTTD is a free and opensource game don't consider that as the same that you can do whatever you want in multiplayer games. Enjoy singleplayer for that.