I think the worst case of this I have seen was a woman (a guest) wearing a white stretch mini-dress, everyone was eyeballing her because:
a) she wore a white dress to someone else's wedding;
b) it was too tight and too short;
c) she was known as the type of person to grandstand and try to steal someone else's thunder - in short =
TACKY!!!!!!
Oh, did I forget to mention the visible panty lines to boot?
My wedding dress was ivory and when I was telling people about it they asked "Any particular reason that aren't going to wear white?" with a raised eyebrow. I would just say "Nope - I just look awful in white! It makes me look even paler than I am so I end up looking ill, ivory is a much more flattering choice for me." Which is the truth, me and white don't get along.
I didn't think it mattered what colour you wore these days.

In fact wedding dresses weren't traditionally white to begin with and that is something that evolved over time.
One of my friends had a medieval theme wedding and her dress was champagne couloured with gold accents. Another friend was married in a red dress with gold toned sheer fabric overlays - it was gorgeous!