ill speak from a CARPET INSTALLERS standpoint.
carpet and the padding are a breeding ground for mold. IDC what people say. ive done some rip-ups that the smell of mold and mildew was literally sickening, making is near impossible to breath. the padding underneath the carpet acts like a giant sponge, taking forever to dry out, and giving all that nasty crap an easy living environment.
you most definatly needed to get air circulation under the carpet, trust me.