I think the situation at San Pedro hotels is like that in San Diego or San Antonio or San Jacinto or wherever -- pools are for hotel guests but sometimes the rule is bent or ignored. In other words, it depends.
I have heard from several hotels in Sandro without pools that their guests in the past were allowed to use pools at nearby hotels but that now that blanket okay is no longer in effect. On the other hand, if one doesn't make a pest of oneself and if no hotel guestg complains and maybe buy a drink or two at the hotel bar no one will say anything.
--Lan Sluder
Belize First Magazine
http://www.turq.com/belizefirst/