The doctor didn't do it for money- he was our team doctor- made no odds to him.
I also know the Royal marines pop their own blisters. They also have an unpleasant method where they draw out the blister liquid with a plastic hypodermic and replace it with Tinc Benzine. This is described a a thick brown caustic agent with the ability to (and I quote) 'make a man's head hit the ceiling from a seated position'. Apparently it hurts like hell, but you can continue with activity within minutes.
Their other, far less painful method it to use a sterilized needle and thread, pierce both sides of the blister and leave half a centimetre of the thread sticking out each end. This drains the blister slowly and lets the flesh inside dry.
A mate of mine (who is a practicing doctor) told me that blisters are generally best left alone when possible. Most of the time this is good advice, but on occasion bursting them is a good idea- if you need to be getting on with something and the blister stops you doing that- the one on my hand was a good example - that would have burst anyway from the pressure of the glove, and in a far less pleasant, unclean way...
Prevention is better than cure- keep things dry, and cover sensitive areas with zinc oxide tape.
As for sunburn blisters, just don't get them in first place. I've been burnt red by the sun, never had blisters though! Use a higher factor sunscreen, and use your head! It's not like the information isn't out there about protecting yourself from the sun. As said in the previous paragraph (and it applies even more so to sunburn) -
prevention is better than cure.
