I have several Jade cactus. I have a white fuzzy growth on the leaves and stems. I clean with a mixture, every Sat. , of 75%/25% rubbing alcohol /water. The deposits turn brown, I use Q tips to do this. Why do I have the fuzzy deposits?
You have a mealy bug infestation - you are doing the right treatment. If the brown spots bother you, you can scrape them off with a thumb nail, tooth brush or a sponge. I do a soil drench (Bayer Tree and Shrub) when I get such pests.
To much alcohol might not be good for the plant--you don't want to kill it along with the mealies. So if you're going to spray it all over I'd probably dilute it a bit. With q-tips though I'll apply rubbing alcohol straight from the bottle since you're applying it only where the bugs are it doesn't get on the plant as much.
Well, from personal experience, I have never killed anything...YET! Maybe my stuff is more hardy since I live in the tundra zone. LOLOL But Michigan is cold too. Haven't had much problem with mealys yet this season in the g'house. However, the whiteflies have taken their place. Need to spray again.