How can I get rid of my cat's bad odor (it is not urine)?

We have a basic cat who is about 3-4 years old (human years). She goes to the vet regularly and has been tested for AIDS/HIV and all of that. All negative reslts. In the past few months we have noticed a smell coming from her. It is a rather bad odor and it is not her kitty litter or anything like that. It smells very strong when she is near you, usually has to be sitting right beside you. There have also been times when after she leaves, the smell remains behind on the sofa. During those times I have found a small wet spot where she was sitting... some kind of secretion? She goes to the vet regularly and has been given a clean bill of health every time. What might the smell be and how might I get rid of it?
Thanks!

First off, welcome to TCS! I hope you will find answers to your question!

I noticed that you posted this same question in the Care & Grooming section, but how about if we address it here and close that thread - since we don't allow multiple threads in multiple forums ...

As to your question, if I had to make an educated guess, I would say she is probably expressing her anal glands. Most cats do this when they defecate, but sometimes, the glands get slightly blocked. My suggestion to you is to have her back in to see her vet (or another vet if you aren't satisfied with the answers you get from the first one) and ask about this.

Hope you are able to get this problem fixed soon!