Um, as described by Bippo, the process is to trap a little of the drink in a
clean straw, remove straw from drink, transfer droplet to mouth and dispose of
straw. No "backwash" issues at all.
I don't do it as much as I should. And by that I mean I should probably do it
with everything I haven't made for a little while, and of course everything
new.
I think it can add a little showmanship to taste it, then grin and give the
customer a wink or a thumbs-up. Or even add a splash of something (sometimes I
just wave the bottle) to look like you are really fine-tuning it just for
them. But yeah, too much may start to look like you don't know what you are
doing - I don't think you have to worry about the alcohol effect at all
however. I'd challenge anyone to get drunk from a pipette when your drinks are
averaging down to 15% ABV.
.dan.