In my experience I'd be surprised if a bill is correct 50% of the time, it's usually nothing major and can quickly be sorted out but on occasion it's a major hassle and something that really shouldn't happen at all. I find US/Canadian hotels the best, but Internationally it's pot luck, in the UK I almost take it for granted these days to "build in" to my schedule an extra 15 minutes in case of having to sort out a check out/billing issue... does make you wonder how much gets billed to people who just pay on corporate credit cards/expenses and just don't worry about it.

T