We looked at this example in class yesterday:

His wife loves her husband

It's mentioned by Chomsky (Knowledge of Language 1986) and the question is whether it's grammatical if the referent of his is the same as the referent of husband and the referent of wife is the same as the referent of her

Naturally, when discussing it you imagine a particular couple and the most likely are the current Prime Minister and his wife/her husband. So we were wondering whether this could mean that 'Tony's Cherie loves Cherie's Tony' iyswim. We then tried a number of tests including imagining contexts such as:

A: Nobody could possibly have any affection for Tony Blair!
B: Oh, I don't know. I imagine his wife loves her husband

This all felt very weird in a context where Tony has just been addressing the British people using a metaphor where he's the erring husband and the people are the wife who's had enough, as reported here

David Aaronovitch's comment on this is worth a read (as are loads of others, actually). You can also get the full text here

B-)