So, for you personally, does shampoo fall into the wet or messy category of WAM?

Just curious. It's not really messy since it's clean, but it's also not really wet since it's not water.

This is a tricky one.

Foam I would say is messy as it's sticky and has a visual effect. Oil and some slime, especially thin and/or uncoloured, appears closer to wetlook.

Shampoo itself I would say is a gunge as it's made with very similar ingredients (xyz-cellulose) BUT isn't messy as it's used for cleaning! In the same way someone putting on a face mask as a beauty product is not WAM in my mind. It's also again not generally coloured so you don't see the effect.

I put it as 'somewhere in between' as I'm too indecisive to choose.

Does it really matter? Messy has turned into naked. Wetlook is still mostly clothed. Yjats what matters.