I used this on my black plastic cowl and the first application was streaky. The next day I did a second application and it evened it up. Overall very pleased and it's held up for a year.
I used it on black plastic trim and found that the initial application was streaky. After allowing it to dry I did a second application. That evened up the streaks and it's held up great for a year.
I have the Wolfgang SCC and it's great. It's several years old and works fine out of the bottle. It isn't going to last over a year though, in wet conditions, less.
In my experience, prerinsing with a hose seems to dislodge some of the contaminants from the paint. IMO that's key. To foam or not to foam, that is the question.
Some companies test in real world conditions. Some of those companies aren't putting a hard time line on their product. My general rule is that what's being advertised should be cut in half for my geographical area.
I don't think it's an issue of who produces such and such product but rather...