Cold selling is my weakest point. So I don't do it!
Colin. In my earlier days, I had similar reservations about protector too. I am now utterly covinced that protectors work, and work really well.
If you protect a fabric, especially one with polyester in it, you are unlikely to get a significant surface bead-up if at all. Often the same with any carpet. But this doesn't mean that it isn't working.
The product I use has a guideline that it's effective for about 5 years. My lounge, Axminster's Dartmoor, was treated once when new in 2002. Two weeks ago my Grandson's potty was knocked over. Terry towel followed by paper towel. Totally dry. No stain. pH tested the next day and it was neutral. Play safe I spotted it anyway. So my protector works well, even if past it's "use by date".
I've started a very easy way to upsell protector. So far this year, I've sold more than in the previous four years :
I might copy the details here after I've published in NewsLink.
Oh, and like Simon, stain removal is perhaps my weakest trade discipline, but if you are realistic of safe expectations and always under promise, you will never "own" someone elses carpet.
Safe and happy cleaning
The Ken