Never worked out why some feel the need to applaud the away fans attendance at the Amex ffs I really couldn't give a shit if they bring 3 or 3000.
I do mostly clap - here are the reasons:
1) To thank them for their money, thus helping keep my ST price as low as possible &/or enable us to buy better players.
2) To acknowledge the kindred spirits who have often travelled for many hours to watch a game of football - us football fans should (mostly) stick together.
3) Who knows; there may be fans in the away end who stuck with us in various ways post-Archer etc? It's nice to recognise them.
4) Away fans often show respect to us (e.g. Newport fans honouring in full the 1 minute's applause for Roy and singing "There's only one Roy Chuter") - I like to show respect back.
5) Why not?
Obviously, there are a couple of exceptions where I'd never applaud opposing team's fans, but mostly I do.