Here's a good anecdote I found in a discussion group:
Back in the mists of time circa 1971 I left school and got my first job as a laboratory assistant for a company that made electric cookers and fires based in Burnley. My job was to sample and undertake quantitative analysis of electroplating solutions and cleaning solutions. I was 17 at the time. Mouth pipetting was routine in those days. Anyway to cut a long story short, I was pipetting 2N caustic soda when a colleague distracted me and I ended up with a mouthful. 2 weeks of nothing but cold milk and cold soup were enough to convince me that mouth pipetting was not the way.
But just for the reasons of showing people not what to do there is some people demonstrating this lost art.
Also I think that mouth pipetting is still used for some purposes. I guess that preimplantation mouse embryos are still mouth pipetted but it increases SAPK/JNK and c-fos.