It is possible to use an Unusualifier with a Self-Made taunt. This does not remove the Community Sparkle effect, but rather attaches a new particle effect to it. This is also visible in the item card. You can use the Unusualifier more than once, and will only override the effect previously applied by the Unusualifier.

By doing this, the item remains in Self-Made quality and by taunting only the attached particle is visible, and the Community Sparkle is not.

Every Self-Made taunt comes with an attribute 134 (attach particle effect) with a value of 4 (Community Sparkle). However, an Unusualifier attaches a particle effect to a different attribute, reserved just for the taunts, 2041 (on taunt attach particle effect). This means that both can coexist.









Couple things to add from looking in the publicly-available SDK code (thanks to Piogre):

People are mostly aware that if you have an unusual taunt you can't apply another unusualifier to it. However, the code that blocks this specifically checks agains the Unusual quality, not whether the taunt has an effect, which means if you have a self-made taunt you can reroll indefinitely as long as you have more unusualifiers (view source).

Another thing, when choosing which taunt particle to render, the game will first check if the taunt has an inherent item-bound particle effect (which community sparkle is not, really), then failing that will check if you have a taunt-effect unusual cap, then failing that will check for community sparkle on the taunt. This means that a taunt-effect unusual cap will override community sparkle on a self-made taunt, but you'll hardly notice because the unusual cap still has community sparkle on it (view source).