The wall suddenly smells like marijuana and stale beer.

Stale beer smells flat and slightly musty. Right now it smells sweetish.

I also guess a few dead little animals. Corpses smell sweetish, the fur musty. Eventually the carcass musty...
Fits!

Thank you!
That sounds plausible... We'll take another look in the attic, maybe you can see from there if it's "just" a dead marten or a rat lying around.
Best regards and thanks for the idea :)

strong flashlight with pick-up

Definitely take a lighter with you. Maybe you'll find the grass hiding spot from the previous owner ;)

I would personally go up wearing a face mask. Honestly!

I personally would go up with a face mask. Honestly!

Yes, and not just a face mask (FFP3 mask) but also gloves + protective goggles. Possibly even in a "full-body condom"... that's what I call the white suits. Rodents often transmit the hantavirus. My daughter had it once, it's no joke! It can, if it goes badly, be fatal!

It is transmitted especially through dust and excrement of the rodents. As I said, having experienced it once, I never want to experience it again. Thank God the doctors were able to diagnose it super quickly back then.

Disposable protective suit please ;) First, it's enough to just look inside with a flashlight. If there's something there, I would get the pest controller or crime scene cleaner :p