I don't get this... I have a 90dpi monitor and subpixel antialiasing on Linux is beautiful.

I should also point out that antialiasing (and subpixel rendering in particular) is designed for low pixel densities. High pixel density monitors do not need antialiasing. (This is why printed font rasterizers such as Metafont do not perform antialiasing.)

I've noticed that on some monitors antialiasing looks fantastic, while on others not. My sister's laptop has a smaller screen and enabled antialiased fonts, and they really do look great. But on my Samsung 2232BW, which is a 22" 1680x1050 monitor, antialiased fonts just look really bad.

So maybe it has to do with more than just DPI, but generally I've read that high-DPI screens have no trouble at all with displaying antialiased fonts. (And yes, I have tried numerous calibration tools, with no luck).

It's likely they have a different pixel color order. If the subpixels are not in the order the algorithm expects, it will look worse than without aa.