I've seen that print of "King of Jazz" too, and outside of the typical murkiness toward the green end of the spectrum, it was superb. So is the Eddie Cantor musical "Whoopee", another 1930 2-strip Technicolor feature: it looks as vivid as the day it was released. These, being "prestige" films, probably stood a better chance of preservation; also a greater number of prints were likely struck off the neg, increasing the chance for survival. MGM, despite its self-proclaimed status as the Tiffany of studios, did a lousy job looking after its films. That's why we have no existing complete prints of "The Rogue Song" and what snippets do exist turned up in the hands of private collectors. If any of "Hello Pop" does exist, it's more than likely to be brief fragments, not a complete reel.
Again, people, we're not saying "Hello Pop" exists, we're just saying there's a very very slim chance some of it may be out there, bits and pieces so brief a non-Stooge enthusiast might not realize what they are or how rare they may be.