cheers Ed. the pub that was in is one i go to once a week and the other punters have learnt not to play WU there any more. so £1 is normally between 1550-2000 in there.
re. letter distribution: a virgin machine tends to give loads of easy letters so it is relatively easy to clear but you won't get a mammoth score. haggard madams which have been repeatedly bummed by Bob tend to give more nasty letters and fewer S/T/R/E/A etc. Z, X and J aren't really a problem as there are plenty of short words which can burn them HAJJ, PIXY, ADZ but Qs normally need the U. JQXZ give extra time to sort out trickier letters like V, C, or too many of the same vowel.
newer shitboxes start at 1700ish for £1 and go down unless someone local can clear, this seems to have demoralised players and it is not getting played as much as before. as for making the grids give you nasty/bonus letters you can only force it to give you them by winning money out before and making the software clam up. It is still rare to have an impossible game. EWQ's website has a tactics section which gives the anatomy of a clearance, not quite the same tactics as i use but it is very good.
http://www.damtp.cam.ac.uk/user/nfm24/tactics.html
if you are interested it might be worth a look.
nobody ever wins on those things.
I was drunk enough the other day to walk away from a game halfway through, so there's my starter for ten! 
