Tubeworker has reported previously [1] on management's decidedly unhelpful hints to ticket sellers. Here's another one ... Always encourage tourists to use Pay As You Go.
The problem? Several stations for very popular tourist attractions - Hampton Court, for example - don't accept Pay As You Go.
It's a good job that the vast majority of ticket sellers have more faith in their own knowledge of the job than in management's silly tips.
Links:
[1] http://www.workersliberty.org/blogs/tubeworker/2008/05/03/fries