Can you test the existence of qualia?
Slap yourself. Ask yourself if it hurt or not. If you can say it did, congrats, you just proved that something fitting the exact definition of qualia exists.
We're not talking something metaphysical there, nor about the correctness of morals, opinions, beliefs, whatever, nor anything particularly philosophical. If you can say you've ever consciously perceived something, be it a headache, an itch, or a taste (say, like "Pepsi is too sweet"), congrats, that's by definition qualia.
Qualia don't exist. Problem solved.
Err... Joe? I know some people seem to have a hard-on about attacking philosophy, but there's no need to go full-tilt <bleep>ing stupid about it.
Qualia is just a name for any experience/sensation/etc that you've ever perceived consciously. If you've ever stubbed your toe and were aware of that it just happened, congrats, that's by definition qualia. If you've ever thought it's a bright summer day, or it's hot or cold outside, or the leaves are turning yellow in autumn, that's qualia. It's not something metaphysical, it's just a funky name for something you experience every day.
Especially since earlier you were against solipsism, here YOU are the one unwittingly arguing for solipsism. Because if there are no external inputs (as in, from outside your conscious mind) that make their way all the way to your consciousness -- since THAT is what you just said by "qualia don't exist" -- then you've actually argued that it all just happens inside your head, and if there ever was such a thing as an actual reality, you've never experienced it. Hell, it's going even beyond most actual solipsism, since most solipsism still would allow for qualia coming from some subsconscious place, while flat out denying qualia denies even that kind of input.
Now you COULD say that we don't need philosophy to learn about how the mind works, since nowadays we do have neuroscience, which goes scientifically about it. But flat out denying even qualia is stupid, because it ALSO denies that there's anything for neuroscience to study there.