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?

Sounds like mealy bugs. The fuzzy is part of the bugs secretion. They suck the juices out of the stem/leaves. When you kill them with alcohol you can sometimes see the brown spots where they were feeding. I use the same technique that you are using for an infestation that I think can be controlled. Sometimes all it takes is a watchful eye and regular diligence with the Q-tips but if the infestation looks pretty widespread, I sometimes resort to systemics which gets incorportated into the plant that bug is feeding on and deters them. Sometimes if the infestation is just in a particular spot, I will cut/prune/remove that part of plant which may stop spread of the bug.
Hope that helps.

I use 100% rubbing alcohol, it seems to work just that much better. I do keep a spray bottle filled with that, and use it regularly. I've found that if the bugs damage the plant, its usually in a new growth spot and the plant responds by making several new shoots/leaves so its not all bad! Also most succulents don't like sitting with any moisture on them, so I do this in the morning usually (even if I see it at night, I usually wait till morning to spray!)
Cheers and hello Paul, I grew up on the east side of Detroit but have family in Dearborn, so know Allen park from childhood!