I've had tons of guinea pigs pee on me. Right on my chest under my nose. I don't think I've ever had a guinea pig have what I would call smelly pee. In fact, I find it not unpleasant at all. Can't quite put my finger on how to describe it, but I guess just some kind of intense veggie smell. So, when your guinea pig pees directly on you on a plain cotton tee shirt, what does that smell like? If you don't know, please try it. lol I would suggest that if it's anything other than a decent organic smell, there may be something amiss with your guinea pig, either health-wise or diet-wise. Once you've eliminated the actual pee as the smell, then I would guess that it's the combination of the urine and the bedding that isn't doing well. Also, when you say litter box, what do you mean exactly? Are they litter-box trained to a small litter box area? If it's soaked wet (in that they are using it that often and nowhere else), then you will need to clean it every day at least. Concentrated urine, no matter what the bedding will start to smell fairly quickly. Also, what kind of litter box? Plastic? How big? It could also be that left-over residue or bacteria from insufficiently super-cleaning a concentrated litter box may be encouraging some chemical reaction sooner in a small area. But, again, I think you need to isolate the problem by eliminating the possible causes one-by-one.
I use wooden pellets, which absorbs urine nicely.
