Although our carpets weren't dirty, it had reached the point of a slight stale smell in the morning if a window wasn't left slightly open every night! A similar smell could be detected when laying down to exercise.
Yesterday we removed freestanding furniture from the kichen, hall, lounge and conservatory and vacuumed throughout.
It took an hour from start to finish then we went out for a few hours to leave them to dry a little. On our return we lit the fire in the lounge and kept the heating on. I think overnight, we shall have to leave some windows safely locked open, to let some of the condensation out!
By tomorrow hopefully, they should all be dry enough to get furniture back in. Personally I think it pays to clean carpets annually or biannually to keep them maintained and in as good a condition as possible.