Hmmm. Worst hotel was the Imperial in Blackpool. Supposed to be this really good hotel where heads of state have been. Rubbish. My room was the size of my bathroom, had furniture that looked like my Nan had bought in 1935, and a small colony of flies that had obviously eaten half of the window sill. Nice. Complained about the flies and they said they would leave a fly spray can in the room. Erm, slightly better service than that please (and they didn't leave the spray in the end)... Totally better to go to holiday inn and places like that if you ask me. Nice swimming pool gym area though.
Worst place though has to be a tie between a new years eve (about 1990) night in a thorn bush on the beach at Benllech, or a lumpy camping site metres away from a cliff (drop) somewhere on Anglesey. Ouch. Luckily in both cases lots of alcohol took the pain (temporarily) away.
Cheers