Why Ad-Aware sucks as hell..

 1. Definition file
 1.1. "Encrypted" with xor \
 1.2. Packed with ZIP with simple password - trivial to intercept def updates
      and change the defs to make the malware invisible
 1.3. No checksum in the def file /
 1.4. Big redundancy in the def file
 1.5. Multiplying the number of entries in the def file with constant 1.46 
      to make it look it has more definitions 

2. Program
 2.1. Poorly written checksum algo
 2.2. Poorly written scanning algo (slow as hell)
 2.3. CSI works only for in-memory images and is useless

You want the proofs? Read the following text ...