Here's my story. About 4 or 5 years ago I was on a website called showcargarage. The website itself is no longer, as I believe it got combined with the
meguiars forums. Not 100% sure though. Anyhow, I came across a thread by Mike Phillips that said there was a mobile detailer who washed Barry
Meguiar's cars with a grout sponge. This peaked my interest. So much that I actually called the guy and asked some questions. David told me he did a test consisting of washing 5-10 black cars with a grout sponge, and 5-10 black cars with a lambs wool mitt. He concluded the cars that were washed with the mitt had more scratches/swirls.
I wasn't sold yet, so I actually went and picked up a few at home depot, which is the kind David used. After using the sponge myself I was a convert.
Now, before my sponge days, I was a loyal mitt user. I came to the conclusion that while mitts pull away dirt and hold it very well, they don't wash out as good as a grout sponge. This is where you get the scratches/swirls, and this is what David was talking about. I also never liked how mitts were so inconsistent. Out of 15 mitts, probably only 4-6 were up to my likings.
Now, is this to say that grout sponges are the best and are for everyone? Probably not. What I do know, is if you like a particular detailing tool, and are satisfied with the results, then stick with what works for you. If that means using a lambs wool mitt, fine. If that means using a grout sponge, fine.
Here's a link to David's website. Let me say that I don't know this guy personally other than when I talked to him 4-5 years ago. I also have no idea if he still details Barry's vehicles or if he's still in business. From looking at his website, it looks the same as it did 3-4 years ago.
Innovative Detailing