You could use a file or hash table to match against, depends on how many 'bad' words you have i guess.

Regex is good also, and allows for more specific and inteligent matching if you are familiar with regular expression (some very easy to follow guides can be found on google), something like...
Code:
on 1:INPUT:#: {
  var %re = /word1|word2|word3/S
  if {$regex($1-, %re)} {
    /echo 9,1 *** Foul words are not permited *** 
    halt
  }
}

"Allen is having a small problem and needs help adjusting his attitude" - Flutterby