I've also found it very useful to bend VmWare Fusion to my will -- between Windows in the guest, VmWare and the OSX host (with high-res / Retina screens), the cursor is often "off" relative to the actual pointer... until I enable the trail in Windows, at which point everything works properly. I have no idea why.
Most cursor glitches end up being a mismatch between hardware-drawn cursors and software-rendered. Turning the trails on forces Windows to draw the cursor in software, which puts the cursor much earlier in the graphics pipeline and makes it much more accessible to other things like f.lux or apparently Fusion's integration.
