I don't blend that much, but if I am going through a spell of doing a bunch of FO samples at the same time, I do try to reuse the plastic ones (don't have glass.) When I have several dozen at once (otherwise I do just throw them away), I have a container of soapy water standing by, and suck the water in and out several times w/each. Then I mix up a solution of soapy water and a little bit of bleach and do it again. By that time the fragrance and the bleach smell is mostly gone (so far as I can tell), but I cannot swear that infinitesimal residual bleach molecules will not make the FO turn into a morphing monster! It has not for me so far, I think, but your results may vary
Also, even doing a bunch of them at once is a pain in the &*^.