One for the experts.....
A lot of what I'm reading suggests that getting a good supervisor is paramount to surviving your PhD. Obviously none of you with bad experiences would have chosen your supervisor had he/she screeched abuse at you in the interview, it happens later. So does anyone have any tips (aside from basic intuition) for how to suss these people out? Key questions I could ask, warning signs, etc?
Bit random I know but it's this our I call the premium rate astro-line...

before you make your decision, you'll probably get a chance to see the labs, talk to current PhD students and ask them about their experiences. If they don't offer you this, don't hesitate to ask.

*Ask how often they would want to see you - as in would you get weekly meetings etc.
*If they haven't seen a PhD student through yet make sure you have a second supservisor who has.
*Again speak to other students - they are usually quite honest.

Fairly simple I think. Ask them on what they expect of you as a PhD student, and also what you should expect from them as a supervisor.

You may feel awkward doing this but it does two things, firstly it will give you an idea of what to expect during your three year relationship, and secondly you can assess your supervisors reaction to an uncomfortable question. You going to have to ask one sometime, and you might as well do it at the start!

I think asking their current PhD students is useful, I was told things my supervisor did and was like which sounded as if he worked in a similar way to me and I found this to be true.

I am also aware of a number of people who have poor relationships with their supervisor that have warned off other PhD students.

Also if you are staying at the same university don't think because someone is a good (bad) lecturer or tutor that they will be a good (bad) supervisor, I know alot of people who have made these mistakes

Thanks to everyone :) It looks like I'll have limited time at the next interview (my constraints not theirs), so I guess some direct questions are a good way to go if I don't catch the students.