Staff turning up for work under the influence from a Hanley night p*ss up was a big issue - and largely ignored - in my time at Towers. As long as they were halfway dressed (often with socks missing) and did not smell of alcohol beyond what extra strong mints could fix, they were good to go. This was ride Operators... not just Hosts.
I've seen Technical Services fitters turn up clearly under the influence to sign Nemesis off. There was one instance where the fully trained fitter was heavily suffering from the night before & gave his keys to the trainee. We [ride staff] told the trainee what to do - with a few errors thrown in so all the harnesses popped open. He then told us to close them, we pointed to the red "Technical Services" sign, so we were not allowed to touch the ride. Our parentage was then questioned as he closed 32 harnesses himself.
Then you got the people phoning in "sick"... they'd get put through to the team leader signing off the ride who would take the tale of the ailment. They'd then tell the Operator "you're without xxxxx today" and it was very common for someone to pipe-up "I saw xxxxx throwing up at 2am in Hanley today". You could not make it up.
All Towers did to try and reduce the drinking culture was move weekly pay-day from a Friday to a Monday, so weekly paid seasonal staff had less money left come the weekend.
There were cases in the Valley at Fireworks where (1) a staff member covered up his uniform and met friends on-park in the Tavern on his 45min extended break (you got one on a Fireworks day). He consumed 3 or 4 pints then returned to work on Nemesis. Case (2) was a staff member who on the final day of season downed about 3/4 of a bottle of whiskey on a break then returned to work. He was literally slumped against a rock at the Nemesis entrance before he was removed by security. He was, however, asked back the next season "as a valued member of staff".
Staff drinking alcohol late in the day whilst watching the fireworks from the Prospect Tower - yes it happened.
Then there were the "Vampires" in the original Halloween on Ice show (circa 2003). They did an elaborate act climbing up / descending from drapes secured to the lighting rig. They did not submit negative tests.
The above won't make comfortable reading for Alton Towers. I accept it happened close on 20yrs ago, but it shows the organisational culture that was in place. All I can say is you can re-theme / re-fit a pub, but you can only change the clientele with a huge change in pricing policy. Towers have always been minimum wage.
