Actually, to be clear, tofu is not fermented in its standard form (the white blocks we usually think of as tofu). There are fermented kinds of tofu and one of my favourite foods in the world is smelly tofu, which is a fermented tofu that used to be commonly sold by street vendors in Hong Kong. It was deep fried, served with chilli sauce and smells absolutely awful, like rotting garbage or something. It's incredibly delicious.
Nowadays when I go back to Hong Kong all the street vendors have disappeared (I think it has something to do with food safety laws) and there are only one or two shops that sell smelly tofu, I suspect because of complaints about the aroma. The places where it's still sold, it isn't very smelly anymore and it doesn't taste as good - it does seem that the smell reflects the length or strength of the fermentation I guess. Sigh.