I usually keep my badge facing in (so you can't glance at my info) on purpose if the badge has a lead-gen attendee type - e.g. founder, investor, media - printed on it. I find that having it the right way 'round makes it harder to have interesting or productive discussions because by the end of the first day everyone is pre-judging the people they meet based on their badge.

If I'm there on a founder badge, for example, it's difficult to chat up investors because they're wary of hearing the 400th pitch from a random startup guy when I really just want to talk and make a connection.

This may be more annoying for me than most because I'm often at conferences as someone's guest, so the badge type rarely matches with my goals for attending.