When one of my guy friends dated a girl I thought was too straight, I would be a total ass about it. I regret that my own weirdness made me a fascist about people who were not weird.I'm of two minds on this. Of course, it's wrong to judge people based on what they look like, just like judging them on ethnicity or educational attainment. Some of the weirdest people don't dress weird at all--they don't need to. And it's never a good idea to bad-mouth someone's significant other, unless they are hurting them in some way and you have to intervene. Not to mention, depending on one's orientation, it could sound like you're auditioning for the job of new significant other in a particularly whiny and passive-aggressive way, which just poisons a friendship.
On the other hand, I've been to get-togethers and such with some horribly mismatched couples (thankfully not so often since college), and I just find it uncomfortable and icky. You just end up only spending time with the half of the couple you have something in common with and hope the other one doesn't show up to future events or they break up. My parents and grandparents both showed me examples of couples with a lot of common interests, so that's what I'm used to. Also, I've never seen or read of a couple that had that whole nothing-in-common thing going for them that seemed to be worthy of emulation.
Not that you can ever have everything in common, and it's good to have other friends and learn about new interests, blah-de-blah-blah. Here's where my dear Dr. S. reminds me that I had never experienced the glory of Evil Dead 2 before meeting him. I guess it's not so much what you've done, as what would be in the broad range of things you can see yourself doing. Like Potter Stewart and porn, I can't express in exact figures how much you have to have in common, but I know it when I see it.