You're supposed to change the oil cartridges in those waterless urinals at least once a year. We had several at one of the places that I worked and the guys said they only started to smell when they were overdue for a cartridge change.
Since I'm one of those crazy people who don't think we should be using water for waste disposal at all, what I'm waiting for is a female-friendly waterless urinal. I'm pretty good at peeing nearly standing up (for a girl), but can't quite maneuver
just right to use a urinal unless I get awfully creative or levitate :P We have a sawdust toilet at our place and it works/smells better not to pee in the poo bucket... it's easy for hubby to go outside no matter the weather, but my pink parts either get bitten to death by mosquitos or frostbitten
Looks like I'm going to have to make a female friendly urinal for our cabin.