Thanks for the replies. It's kind of what I feel - I can't really bring myself to start swapping links with 'Bulgarian dog widget' sites!
I had just been assuming that the value of a reciprocal link was pretty much null if the two sites were of similar standing - IMHO that's how it should be. I link to sites that I like, that's the way it should work.
Having said all that, I do have some more targeted, less precious sites that I might set up a 'useful links, / resources / our friends or whatever euphemism is favoured these days. But, I draw the line at some of the off-topic junk I see on my competitors.