Joe,
Your comments about the red carpet reminded me of a job I did a couple of years ago.
I did the quote at night (winter, under electric lights).
On close inspection following cleaning (in daylight), I could see that the well worn traffic area fibres were actually a different colour to the rest of the carpet. During the quote, in bad light, they had just looked dirty.
The fibres were grey at the bottom, changing to red at the end of each strand.
Re; Powerburst. It's pretty powerful stuff and does not fail very often. Are you putting enough down (or as Tony says, are you leaving it long enough)?