Would teething cause more frequent smelly poopy diapers?

No. Cant see any relationship between the two.
No. But indigestion would. Teething might cause a slight fever, itchiness in the gums, slight pain and excessive salivation .
No. Lots of things can cause smelly poopy diapers (and sometimes babies just make smelly poopy diapers just because they can)... But not teething.