Purple dye tests???? Help

I’m talking about those .88 cent Walmart cheapies. I know pink dyes are the easier to read and more reliable, and blue ones arent as clear, but what about the purple ones? I always hear about blue and pink but never purple? Are they as good as the pink ones or should they be taken with a grain of salt for faint lines like the blue dyes?Sorry if this is a dumb question lol. Also yes the test is dry and this was an evap I’m sure, I just wanted to show y’all which ones I mean.