Lapping beer doesn't work!!?!

[MrJay]

I tried it; starts off well enough, though messy - some does inevitably get splashed up the nostrils, which is strange, but at some point the beer tide mark recedes down the glass and it really becomes quite hard work and then impossible without causing physical injury or breakage to progress further. Which is frustrating, bordering cruel. On the upside a near respectable level surface can be produced, though for some reason I always seem to get it ever so slightly convex. Grrrr - I'll have to keep practicing.

 

[Woody Alan]

That 'll be the meniscus then. I am not sure you'll ever be able to overcome the radiused corners on the surface. It may be worth a try to use some SPA water polish to add that extra sparkle and reduce the water tension which may have an effect on the flatness but I can't speak for the effect on the flavour.
You could also try removing the sparkler prior to pouring to avoid gaseous bubbles distorting the surface. (note people of a northern disposition seem reuctant to do this showing regional variation in flatness results).
HSE warn of the risk of dislocating the tongue and the dangers of overeaching when unguarded. This is at your own risk.

Alan