Here is how your if will think:
1. Let's translate it:
PHP Code:
if ( !is_user_alive( id ) || cs_get_user_team( id ) != CS_TEAM_CT || get_user_flags( id ) &ADMIN_BAN )
If ( user is dead ) OR ( he is not in the ct team ) OR ( he has acces to ban ) do something.
2. Let's see what we will receive: think that first and the second condition are false and the last one true ( or whatever you want ).
PHP Code:
false OR false OR true = true
If at last one of this conditons is true it will go to next step ( the one from { } ).
If we cange it to && ( mean AND ):
PHP Code:
if ( !is_user_alive( id ) && cs_get_user_team( id ) != CS_TEAM_CT && get_user_flags( id ) & ADMIN_BAN )
If ( user is dead ) AND ( he is not in ct team ) AND ( he has acces to ban ) do something.
Now, think that just one is false. We will receive :
PHP Code:
true && true && false = false
If at last one of this conditions is false it won't do the instruction from { } and will probably go to the else ( if it's there ).