Thoughts on “Lobby Cosplaying”?

I recently asked in another subreddit if it was ok to go to a convention with the sole purpose to show off a cosplay…and not buy a con badge. I’ve been going to C2E2 in Chicago for 8 years now and every time, I see cosplayers in the lobby or right outside the entrance in cool and elaborate cosplays to take photos with people. I always thought they bought badges but since they weren’t actually inside the main hall area, I’m now thinking maybe they didn’t? So this year I don’t want to “attend” the con and go to any panels, I merely want to show off a cosplay I worked on this year that I’m pretty sure other people would like to see. Is it an ok thing in the cosplay community to go a convention and not pay for a ticket? To just stand outside in the entrance hall to take photos with other fans? I really don’t want to spend $120+ to be in a hallway for weekend but if it’s considered not cool, then I will. TIA!