It's been a while ago, that I had a liquid screen protection application on my cellphone. But I can tell you that, it performs better than a cover protection. I never had a problem with fingerprints, smudges, or anything else with that phone. I'm considering getting some of the wipe on type, it comes in a bottle also. I have been wondering about putting it on my graphs. I think that I would install a graph glass cover and putting it on that rather than on the screen itself.
There are different types, but most use a nanotechnology. Since cellphone glass has evolved beyond Gorilla glass, I still see a lot of finger smudges and that bugs me to no end.