well if your clutch burning was what was making it smell you would most likely smell the "rotten eggs" whenever th clutch was slipping or shortly after.
i would guess that your cat is probly goin bad unless you are getting the smell only around the time the clutch slips or unless you spilled something in the back.
Exhaust (without the bad cat) is a for the most part not very stinky. If the car is running well (we all keep our cars tuned up right! :p ) and there is no obvious burning of fluids then you probably wouldn't smell it so much. I know i have become very accustomed to the smell of ehaust in my car, but my roommate hates it and can smell it quite easily.
Catalytic converter bad, things to check......
Smell (like rotten eggs) *after* the car warms up (ten minutes regular driving)
does it rattle when you bang on it?
Can you see through the grid inside or not?
Another easy test for a bad cat (works well if its clogged)
Warm up the car
Hold you hand NEAR the exhaust pipe right before the cat.
Take a mental note of how hot it is.
Let your hand cool of for a minute then repeat just behind the cat.
The temperature on a good (not clogged) cat will be pretty similar
The temps on a bad cat will be incredibly different with the front being significantly hotter than the rear.
Also be sure to check out the entire article here.... Good info.
http://www.randomtechnology.com/technical.html
Now you've been a bad cat so go to your pet taxi.......

Rick