What is the trick to getting truly red MMF?

Like any other icing it takes lots of gel color; lots of time to develop and lots of patients(sp?)!
Start w/a deep pink; orange or yellow depending on the tone of red you want. That will help keep down the amount of gel you need.
Remember, fondant dries one shade lighter. This is the opposite of b'cream.

Americolor Red gel...it is the BEST and makes stuff super RED, and no horrible taste like the Wilton Paste. I know you can get it through Global Sugar Art, and I have also seen it on ebay. Good luck! Hope this helps!

I use Americolor super red. It doesn't take as much as Wiltons. I also color dark colors the day before. The color deepens as it sits.

onebigdogmama posted this in response to my post about red BC, maybe it works for fondant too? http://forum.cakecentral.com/cake-decorating-ftopict-357113-red.html+duff

Color your melted marshmallows before adding the PS. It takes a lot less color and is a lot easier on your hands instead of kneading everything

Satin Ice also makes premade/precolored red fondant too if you don't feel like bothering with the coloring...

i use to add colour to my fondant but it affects the taste and can be quite sickly now i airbrush red, black etc... but i will say the powder concentrate is really good...

Satin Ice...LOL!