... Kevin while the grandi groomers are good for grooming the carpet after cleaning, ifyou are looking for something to work prespray in that is better than a groomer for your light soiling situations, might I suggest:
http://www.libman.com/products-highpowe ... ms/179m/0/
or similar design. The mulitple rows of pristles do a better job of agitating prespray and makes prescrubbing go a little faster as well.
In coment to Rick's post.. You guys must have a funny way of grooming in carpet. I've never had my white bristled grandi leave corn rows. :|