This has been the (northern) beer drinker's bane since the return of real ale and handpumps.
When "everyone" drunk beer any pub that used hand-pumps also had the staff with the requisite skill and enthusiasm to serve it properly, or more accurately, how us northeners wanted it, ie thick bodied and creamy headed. Some pubs, mainly Tetley's, had auto-vac systems on the pumps which recirculated the overspill - this countered the spillage problem mentioned by OTD and so a pint could be pulled over until the required serving was had. These systems were withdrawn due to health implications, someone still in the trade will know whether they are illegal, as I know they are available, now that glasses are not re-used. Tetley's also had a regulation pull through of so many pints per pump per session at one time, now of course the lines are "on" more or less all day.
When handpumps and beers started to re-appear after the keg and lager hiatus it was sometimes quite difficult to get a decently pulled pint. I can still remember the faces, and some of the names, of the staff you would avoid - the ones who gave you the pint as exactly described by ecbd going back to them dark days. Your face would drop if they were the only one on that night! But it can still apply now. Most lager drinkers think your just a pillock if you go on about this issue.
The correct tightening of the sparkler, and a greater effort were generally all that was needed. I think that as less people drank beer then less people understood, or cared, how the finished, pulled pint could vary in the mind of the drinker as it was seemingly the same stuff from the same pump. This thinking would obviously apply to some staff as well. It's odd that the stereotypical barmaid would be one you wouldn't want to take a punch from and yet the modern thinking is that pulling the pumps is a sort of easy-peasy no effort kind of thing. I've put that as politely and non-sexist-ly as I can think of.
I have theory of my own regarding glass washing and detergents, relating to the change from those spinning glass washing machines to the ones used today as I have noticed how the head retention improves if you can "keep your glass" - up to a point.
As anyone who has worked behind a bar will know the actual skill in pulling the pint is pretty easily learnt and I'm sure all staff are taught correctly by the manager/landlord (to suit the locale of course), I just think there's a generation who don't "get it" and might see anyone who complains as over fussy. With the upsurge in interest hopefully this will become a thing of the past.
