Yeah well the general idea that the poster was looking at is making a clear taillihgt red.
The rule of thumb is if you have a hard time in the slightest bit seeing your brake lights in the daytime they are too dark.
There is allot of tailights out there that have the slightest shade of tint on them and the only thing you notice is how uniform the glow is rather than how prism'd it is.
Some guys like the dark shade to go with the black car, some guys like the super light tint dusting to uniform the lens into one glowing entity rather than a bulb induced section.
To each his own, I like my taillights as bright as they can get, but at the same I hate faded 'pink' taillights even more.
If your not sure what pink taillights look like, take a look at ALL dodge intrepids up to year 97 or 98 I believe (the first body style). Dodge messed up by using a a tint on the intrepid tailights that faded with any contact with the sun...like at ALL!