Nigel,
Protector costs as much as you price it, surely!! As you say, if it's done properly it is of fantastic benefit.
In a lot of cases it doesn't "cost" at all, it saves. Avoiding a £50 or £100 excess on an insurance claim is one such example, like Garry mentions above. A protected carpet will have far fewer spots and marks on it over the long run, providing the customer follows advice and deals with them as they happen. It'll look better for longer and not need replacing so soon.
If they don't follow the advice given it's their fault isn't it?! You wouldn't knowingly run your car tyres at 15psi and then complain because they wore down prematurely. You didn't follow the manufacturer's guidelines, so you pay the penalty!
Drying times.... The amount of extra moisture from a protector shouldn't present any problem at all if the carpet has been cleaned diligently, it should only be slightly damp after extraction. Potential problems from moisture, i.e. browning or mildew should still be way out of question, even if protector is applied straight after extraction!
You don't have to
waste time with airmovers. Clean a room, put a fan in there whilst you clean the next room, protect the dried carpet, and so on... anyway, you don't have to have completely dried the carpet off before you protect it, in some ways a little moisture there helps out.
3. No matter how much you tell clients its not bullet proof' - they always want to believe it is
That's a fault with the way it's sold to them, not the client. It's not hard to reinforce an important point so they remember it.
4. If they drop hair dye on the carpet it makes no difference whether it is protected or not. So which stain is it that can only be removed if the carpet is protected but couldn't be removed if it was not protected.
Again, a fault with the way the product is sold to the customer. Tell them the benefits, tell them what it can and can't do and they can be left in no doubt.
Why the need for lab tests and scientific statistics??!!? Field testing is the only proof IMO and after nearly 18 months of said testing on my own carpets, as described above, I've got absolutely no moral problem with selling protector at the price I sell it.....
because I only sell it in the right situation!