As I recall, "Blue Stuff" was a spray abrasive in a can. It was like a
silver polish for the contacts, and will work well on SOME types of
switches that are heavily corroded. You would NOT want to use it in
posts, as you might polish the carbon track free of carbon. It was a
product of last resort when gentler cleaning methods were not enough.
Freon is not magical stuff. It did work well, but went away because of
environmental concerns. I'm not sure that some of the 'freon
substitutes' aren't nearly as bad.
Current cleaners also will make you finger feel cold when sprayed.
Regards,
Tim
Bristol Electronics