*At least on member of station staff took pleasure in misdirecting a bike once -years ago at Bath I was sent to the wrong end of the HST... The first time I used that station. Ever since then I've done my research on where I needed to be ahead of time and asked penetrating questions of anyone telling me something I didn't expect!
Just once?
I've regularly been surprised by the occasional substitution of an HST for a 91 on East Coast, where the cycle storeage is at opposite ends. Although I will often ask dispatch staff if I'm in any doubt, I do find I'm occasionally mis-informed (because they, in turn, had not been informed of the substitution). It does lead to a bit of panic on the platform trying to get through a crowd of passengers from one end of the platform to the other! Fortunately, this is only likely to happen to me at Newcastle, Edinburgh (or the Kings Cross terminus) and, as each of these involves a crew change then the Guard is as likely to be equally mis-informed and standing with me at the wrong end!
There's generally more chance of an FGW HST travelling in reverse formation, but again, platform staff should be aware (and indeed announcements to that effect at FGW stations seem to be quite reliable).
I will agree with Flamingo that I do see a number of other passengers with cycles being less that prompt in loading their cycle, sometimes only starting to sort out their bags and tickets after the doors are open for them. I'd hope that such passengers learn after their first experience of taking a bike on the train and become more efficient, though looking at the way people drag enormous cases through coaches and leave them blocking doors and ailes, I'm not so sure.