Mine will have some odor right when it is "fresh". The only time I've had a really stinky poo was when I fed my boa chicks... Man...the smell. I'd say if the poo smells horrendous, or is very runny / diarrhea like, then you might need to go in to the vet for a fecal or something just in case.

If you have lingering odor in the cage, I'd suggest doing larger spot cleaning (removing all the poo but also a large area of substrate around it) and possibly using something like a vinegar / water solution to clean the enclosure. Some plastics can absorb odor and that may help. My parents have a litter box for their cat that is like this. 2 weeks after first using it (with daily scooping) and the plastic had already absorbed enough bad odor to smell like vomit...even with fresh liter in it. I have been using a litter box for 7 years now without any residual odor because of the type of plastic (it gets scooped daily).