Most airlines will not accept pain in hold luggage (even if it's not classified as dangerous goods) simply because of the damage it can cause to other passenger's property if it leaks.
Exactly. Even if it were safe and legal it is not the best idea to put big tins of paint in your baggage.
Once I was waiting for my bag when I noticed that many of the bags on the carousel were covered in some sort of sticky glue. Distraught passengers were saying "oh no, my bag, my bag, all ruined..." (Mine was ok luckily) as they emerged and then finally a large tin with no lid appeared on the belt and two men started saying out loud "oh no, our glue, our glue, all gone!". If I were them I would have vanished discretely without saying anything.