People that overuse deserve to be talked to and asked to tone it down. I've seen a couple of instances of this in my time and it works, as most people are a little embarrassed to learn that their perfume/cologne/body spray is that pungent. Fair enough, considering that once you've used the same scent for months on end, you barely smell it on yourself anymore. Sometimes it takes a gentle nudge to inform.

And yes, if once talked to, someone continues to bathe themselves in scents that gag other people, they need to be let go. The flagrant disrespect for people who have to be around you for 8 hours a day is too much.