I generally hate scalp scrubs but really like this one
I have found most scalp scrubs I've tried to be very disappointing; basically sea salt shampoos with large chunks of salt that just fall on the ground before they even make it to the scalp, or hard grains like nutshell or coffee that are difficult to work into the scalp, causing you to apply excessive product to get it to work, then get stuck in the hair and take forever to rinse out.
I have ridiculously thick hair but found Scalp Spa Scrub quite easy to work in, the perlite is grainy enough to feel like you're getting a decent exfoliation and rinses out a lot easier than other scrubs I've tried. A bit of shampoo is all that's needed to get any last few stubborn bits out.
What I love most about this is how my head feels after using it. My scalp feels tingly and SUPER clean and uncongested. Hair feels soft overall and my roots feel like they have a healthy, natural boost to them. I recently tried Kerastase Chronologiste Pre-Shampoo which is a charcoal based exfoliant, which is nice and easy to work with, but I feel like the Spa Scrub is more effective at exfoliating and the effects on my hair and scalp are more noticeable. I will definitely repurchase this when I run out. I might even try the matching shampoo at some point, too.