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.