You're right Murray, this only happened once, when I first got them done, they've never used the thing since. I can't say for sure it was a UV lamp or just some random gadget with a blue bulb in it, but it's not there now and they assured me they only do acrylics so I'm happy with that.
Maybe I got a junior trainee on my first visit who didn't know what she was doing, or perhaps it was a "let's bullshit the bloke" moment and charge him extra for a "blue bulb treatment".
There's a whole world of smoke and mirrors in the "beauty" industry.