Question: what is the best carpet cleaning solution for machines?
Answer: Bissell 78H63 Deep Clean Pro 4X Deep Cleaning Concentrated Carpet Shampoo, 48 ounces - Silver. ... 
Carpet Miracle - Concentrated Machine Shampoo, Deep Stain and Odor Remover Solution, Deodorizing Formula (32FL OZ) ... 
Nature's Miracle Deep Cleaning Pet Stain and Odor Carpet Shampoo.