Rule advice please

[Mike Grau]

Hello.
Following discussions on this list about obfuscating words to avoid spam 
detection, and not being a ninja, I'd like some feedback about the 
possible efficacy or pitfalls on rules like the following.

As noted in other discussions, words with scrambled letters between the 
first and last letter can be caught by checking the permutations of the 
letters:

     /\ba(?:ess|ess|ses|ses)s\b/i   <-   finds permutations of "asses"
	
However, this quickly gets unweildy when building a regex checking all 
the permutations of more than 5 letters. Couldn't one use a regex that 
simply looks for the letters used and uses a negative look-ahead 
assertation to  eliminate other words of the same length by first 
running the expresssion through a dictionary of words and phrases. For 
example, a rule for the word "exploited" after run through a dictionary 
of 617709 words and phrases:

    /\b(?!exploited|elliptoid|epitoxoid)e[xploite]{7}d\b/i
or perhaps an additional rule for added letters "expploited", etc.
          /\b(?!epileptoid)e[xploite]{8}d\b/i
          /\be[xploite]{9}d\b/i
or combined:
  /\b(?!exploited|elliptoid|epitoxoid|epileptoid)e[xploite]{7,9}d\b/i
Usually the obfusticated word still resembles the word with the meaning 
the spammer wants to convey. I doubt the spammer wants to use the word 
"elliptoid", and anyway, the idea is to use these rules as non-scoring 
rules for use with meta rules.

    (OBFU_EXPLOIT + RULE1 + RULE2 + RULE3) > 1   etc.
or whatever. Thoughts?  Other samples:
  subject =~ /\b(?!cartoon|croatan|carroon)c[arto]{5}n\b/i
  subject =~ /\b(?!downloadable)d[ownladb]{10}e\b/i
  subject =~ /\b(?!dripping)d[ripn]{6}g\b/i
  subject =~ /\b(?!ejaculating|enunciating)e[jacultin]{9}g\b/i
Of course, you could add "1" and "0" in the character set if the word 
contained a "o" or "l", and the like.

-- Mike