I normally use Wilton coloring for cookies and cakes that I do, but it always seems to turn everyone's mouths whatever color I use! I see a lot of people on here like Americolor, do that turns everyone's mouths colors too?! 

I use Americolor, a little goes a long way and  no aftertaste. The first time I made a red velvet cake, I followed the recipe which used 1 oz.  of red food coloring, and boy we had red teeth and mouths, yuck!!! Since then I cut down to 1tsp and have a nice color and no red teeth or mouths. That was the only time I had that problem using the americolor super red, but that was really my fault since I did not need to use as much as the recipe called for.

I suggest you are making your colors much too 'dark'/saturated w/color.  Try using less but make it at least the night before using.  This will give the color time to develop so you can use less & remember most colors will darken  one or two shades once on the cake/exposed to air so again you can use just a bit less.  Most people find lighter color much more appealing than bold, bright ones in regards to fool.  To help in making red do not start w/white but tint it pink (or yellow or orange depending on the shade of red you want) 1st...be generous w/this color.....before adding any red.   

I do tend to use a lot of coloring with the Wilton so that may be the problem. Thanks for the advice! I will try that!

With regards to making a deep red colour, I haven't tried this yet but I did read somewhere that if you make a paste with cocoa powder and red food colouring then you can get a really deep red without using so much colour. 

Hopefully someone who has tried that can chime in there and say whether this actually works or not.