I take offense to that comment Sue! Mine has few to no streaks in it, I just used dawn dish soap to get all the armorall crap off it and then smeared it on with a brush from HF. I think those with streaks are having issues with repeated spray on products that are saturated into the plastic, preventing the etching of the dye.
I think the real issue is to remember that it is a dye, not a paint. If you are doing multiple coats, you are using it like a paint, therefore it will scratch off, peel off etc...if it is dyed into the plastic, I can scratch mine and fairly deep it stays black. That means the dye soaked into the plastic. I have to wonder that if by diluting, you are minimizing the penetration of the chemical.