NOOOOOOOOOOOOOOOOOOOO!!!! Don't use WD-40. It DOES work, but you are teaching the customer to do it themselves. Use a gel solvent and tell them it's not sold in stores (which should be true). Most customers are absolutely intimidated by carpet. You want them to think you are doing something special they can't do on their own. Which actually is a fact. If they see you use WD-40, the next time they have a stain they will hose it down and delaminate their carpet. Please use industry specific products! It helps the rest of us!
As much as I hate to admit it, I have used WD-40 in the past. But only in vacant homes or apartments, and only when I ran out of spotter! It does work, but I can feel the carpet cleaning Gods' frown of disapproval on me.
