What do you need to know about potential supervisor's publications when attending an interview for a PhD? I have been advised that it is a good idea to read papers written by a potential supervisor before having an interview with them for a PhD position.

I can make sense of the summaries and introductions, but that is all. 


Do supervisors ask applicants about whether they have read their papers?
Do I attempt to summarise vaguely what the paper is about? 
What sort of questions may be asked about papers? 
Can you just say something along the lines of  ' I find it very interesting that you did a recent article in ????' for flattery?
I would, in fact, ask the opposite question: Why would you want to work with someone if you are not interested in their work? Of course, I wouldn't hold an oral exam or something with a prospective PhD student, but I would hope to be able to have a substantive discussion about my field with the student.

Thus: I wouldn't ask "Have you read my work?" because to me, it would be obvious that the student has read some of my work. Out of interest, not because I asked for it. 

BTW: I wouldn't recomment you to say something along the lines of 'I find it very interesting that you did a recent article in...'. Say something substantive, challenge me, tell me why you are not convinced by that article, ask me about it -- yes! But don't try to flatter me in a blunt manner.

Good luck with your applications!