That throws a new light on the situation then! If there actually isn't an identified infestation, all that's needed here is a little marketing spin
If you clean with colloids (e.g. m-power or nemesis) combined with thorough HWE you can legitimately claim you're using products and techniques proven to effectively eliminate these sorts of problems. No extra hassle, expense or need for gas masks and white suits - just a decent price for the job.
P.S. Derek, maybe he was asking Colin to do a bit extr for "flea" ?