I've tried multiple pairs of red+blue and red+cyan glasses, and have yet to find a pair where the red side can effectively block "pure blue" from a monitor, and the blue side can effectively block "pure red" from a monitor. That includes every photo posted to this sub, as well as my own Photoshop experiments with trying to determine ANY level of "pure rgb red" or "pure rgb blue" that's effectively black when viewed through the other lens.

Have I just had really bad luck trying to find a pair of glasses with sufficiently narrowband color filters to work? Or do I have wildly unrealistic expectations?

I know that historically, blue light from CRT displays was spectrally "sloppy" and surprisingly broadband (with substantial energy well into the cyan-green portion of the spectrum)... but I've also gotten the impression that "LCD-blue" is a lot "spectrally tighter" than "CRT phosphor blue" used to be.

If clean R+B from a RGB display with basically no visible crosstalk is possible... what do I actually need to look for in a pair of glasses to not end up with yet another pair that's basically useless for the intended task?