What? Seriously? I think you'd risk looking like a tool if you dress clumsily to avoid not looking dressed up - that's a tool. This is much along the lines of Manton's thread "Worst Look"; don't dress like every other person who shoots for the lowest acceptable level, if they don't want you in a suit they'll say "Please don't wear a suit".
Yes. Seriously. I never said to "dress clumsily to avoid not looking dressed up" i was saying he should be appropriately dressed for the occasion. I probably should have added that he should ask what is expected of guests. Lets put this into a different prospective 50-60 years ago if you were invited to a wedding in england and the attire they requested was lounge suits or w/e they called what we today know as a suit, and you showed up in a morning coat because you didn't want to "shoot for the lowest acceptable level" and then you claim well you should have said "please don't wear a morning coat" how would that make you sound?
P.S I'm totally in agreement that there should be a return to some form of formality in dressing. For me i really don't understand why people don't like wearing suits, in essence a well cut suit hides what is physically wrong with us, be it dropped shoulder, higher waist on one side, sloping shoulders, big chest/stomach etc and i have no idea why people are satisfied with a dress shirt, slacks, and a pair of square toed shoes. But with that being said you should respect the dress code set by the wedding party and if its unclear you should ask