Do I need a 'dedicated bathroom paint'?

When people think of needing a dedicated bathroom paint, what they really mean is needing a paint that is easier to clean, as your standard flat matt will pick up more grime than a higher sheen finish, as the higher sheen will allow for easier cleaning of the paint.

For instance the Auro Natural wall paint 555 is perfectly good matt flat emulsion, but you may find the Auro eggshell 517 for walls and wood will be easier to clean:

The Grafclean Eggshell is probably the best all round choice and cheaper than the Auro eggshell 517.

However the Auro 555 is perfectly fine in reality! It's just a flat matt, so will pick up dirt more quickly.

So in summary it's more to do with the washability and sheen than the 'type' of paint.