From Scheduling Alert 13-08-1:
During each required 10 hour rest period (#2 above), a pilot must determine whether he has received a minimum of eight consecutive hours of sleep opportunity. Any disturbance, such as a fire alarm, phone call from the company, etc., requires him to determine whether his sleep opportunity has been interrupted. For example, some pilots may have no problem returning to sleep after hearing a fire alarm, while others may find it difficult to get back to sleep even if the interruption was short. A pilot who is unable to get back to sleep would be required to advise Crew Tracking or Crew Scheduling that his sleep opportunity was interrupted. The rest period would no longer satisfy the requirement for 10 hours of rest with eight hours of uninterrupted sleep opportunity, and the pilot’s schedule would have to be adjusted as necessary.
So if the drunks in the room next to me wake me up at 2AM and I couldn't get eight hours uninterrupted sleep, it's not a call for fatigue, it's a call that the FAR can not be adhered to. IMO, it wouldn't hurt for DALPA to get some insurance on this point and make sure it's made clear in our PWA, rather than let it go and hope for the best (i.e. leave it to the CP to decide if you should get paid because the CP decided it's a fatigue call rather than a situation where the FAR could not be complied with).