I'd be less concerned with the infection risk than with practicality and appearance. After all, my white coat is hardly sterile by the end of the day, but I do wash my hands regularly and don a gown when there's a MRSA risk.*
But my white coat does get visibly besmirched regularly, and it's lovely to be able to just chuck it in the washer at night -- gotta love those tough poly-cotton blends, even if they feel kind of icky. A suit, however, would be much more of a pain to deal with. I guess I'd have to rely on multiple copies and frequent trips to the dry cleaners.
I actually like the idea of doing a residency in a place surrounded by cornfields, and the weather would be an interesting, um, challenge. But the dress code worries me. Mayo sent me a picture-filled brochure for fourth year visiting student rotations. Everyone was wearing suits and look all formal, business-y, and noticeably smug -- absolutely not my kind of place. Yet I'm aware that promotional brochures often do a bad job of capturing the spirit of a place, so I guess I'll just have to check it out for myself if they interview me for a residency.
*Interestingly, Duke has a policy of gloves and sterile gowns for all known MRSA infections, regardless of source. The VA hospital across the street had a similar policy but discontinued it in favour of gloves and sterile gowns for MRSA open wounds only. The rates of MRSA infection at the VA actually went down significantly.