I have asked my Tunisian pal his opinion on this subject. He put himself through university working at the resort hotels during the summer so he has several years of experience. He is a very western thinking, educated, young muslim male.
A native Tunisian could never afford a Hammamet holiday. A software engineer working in Tunis makes 480 dinar a month. How far does that go in a resort hotel. While they are grateful that Europeans are bringing their tourist dollars into their developing country, they wish it could be done with a little more respect. Picture a boorish American in Europe - (no offence to any of our american posters) Well, change the picture and see topless sunbather on a public Tunisian beach.
Given the levels of animousity in the Muslim world to all things western, it might be a consideration to try and moderate our behaviour as a sign of respect to a country and their customs- even if it means a few tan lines. After all, we are guests in their country.
Poolside... I think the hotel staff might have to extend the same level of tolerance that the tourist expects from the Tunisian public.
besides girls,... sun tanning destroys your skin!