I was very unhappy to discover a few days ago that "spam" == 0 returns true. Unbelievable... you can compare a true value to a false value and PHP will say they're equal. (What were they smoking?)
I haven't tried the comparison above, but I have used the following many times ...
if ($a) // THIS IS FALSE. $a has no value yet
$a = "spam"; if ($a) // THIS IS TRUE
if ($a == "legit") // THIS IS FALSE
