Carpet cleaning

Anyone have a positive experience with a carpet cleaning company? We have several "dog" spots that need attention.

With two dogs, we get our carpet cleaned twice a year so we have quite a bit of experience with this subject. We've tried several companies, but for my money Carpet Max seems like they do the best job.
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Any other recommendations on carpet cleaner's? Commercial (experiences with Carpet Max) or do-it-yourself carpet cleaning?

Thanks