I have used Deoxit for years on my boat and in my garage. In most cases it is great stuff. I will say that I have had several connections where some heat is generated and the Deoxit turned into a thick varnish like substance. Since they were on Marine applications I didn't think it was necessarily bad because it seemed to seal the connection better. Once I had to take them apart though I had to chip some of the stuff off in order to get a good connection going back together.

I would not apply it to any circuit or connection in my HT simply because it may do just like Altec pointed out earlier and make the situation worse. I find that most connections in my HT can easily be improved just by disconnecting and then reconnecting the male/female type connections as most are self cleaning to some degree.