I must say, being a security guy looks really really boring and lonesome to me! I had to be at a client today (and yesterday) and what I noticed was that every time I signed myself in or out, the security guy was soooo fr*cking grumpy! He would look angry, talk angry (throw with stuff!) and not be friendly at all.
It was actually pretty funny because every time he got unfriendly I got more friendly :-). That resulted in an even more grumpy security guy.
Conlusion? Never become a security guy unless you are really really sure that you like it, because it is very lonesome, boring and frustrating if you do not :-).