I am making a cake for a competition and will be using cake dummies for the main cake.
I also am thinking of using rkt for some of the decorations. This will be a cake that will be on display later on and I need to know will rkt's go "bad" after a long period of time if covered in fondant?

Should I just carve the shapes from foam instead?

Thanks for any tips or advice in advance!

I would think that, as long as no one is going to eat them, you should be fine. Hopefully, someone will chime in who has used RKT for a competition that can tell you for sure.

They do taste off if they are really, really old. Don't judge me.

If you mean will they go bad in the sense of growing mould or breaking down into a soupy mess the way a head of lettuce will if left too long in the crisper (You know you've done it on occasion--so don't judge me), the short answer is "no".

In terms of heat and humidity they might tend to slump if the marshmallow in them gets warm enough to melt, but that's going to take a lot more heat than normal room temperatures.

In terms of flavor, Leah is right about the flavor. When they get really really old they're likely to taste about the same as the styro dummies that you're using for the main cake, only sweeter.

yeah- as in 'moldy' falling apart bad....not taste bad. I hope no one tries to eat it!
I just want it for long term display--display, not eat. lol

They'll be fine for display