As a pest controller for 13 years and stung by wasps and bees thousands of times and I have never heard of this. personally I think it is just a myth, I tend to to think that if this was true, the whole world would know about it, probably 70% of the bees & wasp nest jobs I went to had someone that had been stung, if this method actually worked, I'm sure just one of them would have known, or surely it would have been mentioned in one of the many courses I went on?
Many people get stung by wasps and bees and after the initial sting show no other symptoms, the only problem I ever had is the sting would itch like a bitch for a few days, and it is also normal for those that get stung and swell, for that swelling to go down quite quickly.
I think the fact that this is not public knowledge says it is just a myth and doesn't actually work, maybe a bit of placebo?