There is a "cat spray" smell in my house only at night. The smell will begin a few hours after dusk and by daybreak the smell is gone.
This smell is mainly in the den, which is a converted carport. The adjoining living room also suffers this same smell. The bedrooms on either side of living room do not smell at all. The conversion was done sometime in the 80's. I have lived here for 7 years and for the first two years we did not notice this smell.
Please help! This is driving me crazy!

Possibly critters under the carport

Cats roam between dusk and dawn.

That's when they do their business.

Probably just some neighborhood cats marking your house as their own.

You can find cat repellants you can spread around and under the house at big box and hardware stores.

To add more detail to this...

We recently had the house tented for Termites.
The strange smell went away for three weeks. The smell then came back gradually over a week. Now we are back to Square 1. Bad smell nightly from dusk to dawn.

I want to think there are some kind of insects/pests that were killed by the fumigation, but came back.

Anybody have any ideas?

Ask the termite guy if he has ever run into this before after tenting