Help me make red icing!

[Bakingdisaster]

Hi, I have made my son's birthday cake, and went to ice it with pre bought red fondant, and I cannot use it, as it tastes sour and disgusting, and will ruin the cake.
I don't want to make more buttercream, hoping to avoid this as in abit of a hurry, and ran out of butter now. I was wondering if I made red icing using icing sugar, water and food dye would it stick to a dirty iced cake without running and showing gaps?

No, that would more than likely be an absolute mess. Red fondant often tastes a bit unpleasant together with other strong colours like black/navy however when you have rolled it out thin and it's only a small part of the overall taste of cake it's usually fine. Eating a chunk off the fondant straight out of pack is never good with deep colours. I'd go ahead and use it, I'm assuming it's in date and not actually gone bad, packaging fully sealed and all that?

Yeah agree, strongly coloured ready made icing often tastes a bit strong.

You could buy some white ready made and colour it with the red paste but that would mean more shopping,

The water icing you suggest will not cover the cake, sorry.

By the time you add enough red food colouring to white to make it red it will taste the same, possibly even worse as the premade stuff uses concentrated colour and what you buy will probably be just ordinary strength so might end up using loads and have sticky mess! I bake a lot and always buy premade dark colours, it's borderline impossible to get a good dark colour with proper consistency otherwise, even the bought ones can be harder to work with as there is so much of additive in the colouring.