1. Its very existence. The fact that areas are taped off is apparent when you get to such an area. And find it taped off.
2. Off! Not of! Twats!
3. Even without the typo, this sign doesn't actually make sense. "Various areas taped off thanks". What? What are we supposed to do with this? Where's the verb? What's the point? What does this sign tell you? It tells me that some people are too thick to operate chalk. Maybe they mean "Some areas can't be used, sorry about that" or "Leave our tape alone" or "Thank you for your patience while we paint".
I suggest a new sign:
"Things may exist."
To go with the general purpose laminated sign:
"Don't be a twat."