Possible Clogged Cat Converter

[Broslice]

I think my 95 celica gt has a clogged converter, it has a slight rotten egg smell when i whiff the exhaust. There is no noticeable performance loss.

Question: What causes a poisoned/clogged converter?

Question 2: If i replace it, will it just happen again?

[Pineapple]

Cat don't really get clogged unless all you do is very short drive. Take the car out for a long drive on highway and see if it helps.
Cat will get broken. Its ceramic and if a stone hit it or you hit a big pot hole, it may shatter.

[Broslice]

I have driven it on the highway for about an hour, there is a burnt rubber smell and i pop the hood and can see a small amount of a greyish smoke down below the cat converter.

[Pineapple]

Got a leak? Did the engine cover under the car touched the exhaust?
You can remove the cat and check gasket and the ceramic. You should be able to see a grid inside.