I recently ditched a 4-year old Giro Stylus helmet. I was drying the pads each day with a paper towel, and removing and washing them regularly, but they were still getting smelly after a couple of days. The pads were starting to fall apart a bit too. Not bad enough to warrant changing the helmet, but a strap anchor started pulling out through the foam so it had to go.
A bit of searching for stink-free helmets led me to the MET Sine Thesis helmet.
http://www.met-helmets.com/index.php/range-2011/3-sine-thesis
Shockingly expensive (and maybe tricky to get outside Europe) but it's the only one I could find that uses a series of gel pads all-around instead of foam pads. Some of the cheaper METs have the gel pad at the front, but fabric ones everywhere else. The gel pads seem to be available online with a bit of searching.
No more helmet smell. Online reviews all say it's super-airy, lightweight etc - I can't say I've noticed, but I haven't worn it on a really warm day yet to test that. I have occasionally heard wind whistling through it, which didn't happen with my previous one.
Only downside I can see is that the biggest size isn't all that big. I'm a 60cm head, the 'large' size supposedly goes to 61cm. I've had to do some careful shaving of the foam inside the helmet in a couple of spots - I seem to have a slightly squarer-shaped head than whoever this was designed for. Happy with it now though.