When we went to sign a contract for some building work (with a design and build company), we noticed there was a non disparagement clause. So you can be subject to litigation if you write a bad review. It seems unfair and after a bit of googling, I saw that this isn't even legal in other countries. I've heard of non-disparagement clauses in contracts between employee and employer, but not in this context. Has anyone come across this before? Is this common when it comes to builders?