Do you really need special coloured hair shampoo (if you have coloured hair obv)

[lummox]

Has anyone with coloured hair done an experiment to see whether it makes any difference whether you use special shampoo?

Am trying to find really nice smelling shampoo for coloured hair and not getting anywhere. But there are loads of nice smelling ones that don't specifically say they are for coloured hair. Am wondering whether they would in fact be fine?

I do because mine is red.
I use Matrix keep me vivid and my hairdresser actually told me I'm the only one of her clients whose colour doesn't fade!
It's a bit more expensive than usual supermarket brands, but you only need a small amount so I think it's worth it