It is not exactly a common problem for us as we rarely use hotels with the children, but when we have done, I recall being disturbed by fellow guests at 2 am so if my children disturbed them at a more reasonable hour, I am not going to worry about it.
Would depend on time and circumstances. I cannot tolerate my kids screaming and shouting after a certain time (usually about 9ish in the evening) as I need to unwind in peace and quiet and with several glasses of wine )but I know that in a different environment to home, my kids are really excitable and hard to settle. If they were just making a little noise, personally I wouldn't mind but if they were, for example, racing around a bar or restaurant at 10.30, I would be a bit annoyed at this interruption of my 'grown up time'
Just remembered my last ferry crossing to mum and dad's in Newcastle where I was kept awake by revellers until about 2 am then woken up by kids in the next door cabin screaming and playing very loudly at 5 am! Hardly relaxing but what I've come to expect on these journeys and at least I can hand my kids over to my parents once we arrive