What's Sihankouville like?
Its Business come r & r round Cambodia and Vietnam, i dont live there but have been in country around 6 months over the past 4 years.
WikiTravel gives the most reliable view as opposed to the bulls#itting Lonely Planet. The write up states that the beaches can be dirty though this relates to disgarded litter from western tourists, the locals sweep the beaches twice a day cleaning up after said western tourists.
If you want any more specific info, PM me, happy to help.