Are shelf-stable probiotics worth buying?

I don’t think there’s any way to tell for sure. I take a generic Florastor that I get from amazon. Also a Reuteri pearl and Schaffer’s daily advantage (also from amazon). My feeling is that if they’re not horribly expensive and they’re not hurting then maybe they’re doing good and maybe they’re only doing me psychological good via a placebo effect — but whatever works right!

For me it isn't so important if the probiotic is refrigerated but what other crap is inserted into the powder or capsule. For example I used to find the Lactobacillus rhamnosus GG (LGG) in Culturelle to be very effective. But that was years ago before Culturelle changed the formula by adding a bunch of crap into it. Here are some studies but please note that they are over 20 years old when the probiotic was relatively “clean”.
 
A 1997 study of 245 adults who took LGG or placebo to prevent diarrhea when traveling to various countries showed that those who took LGG cut diarrhea risk almost in half.

A 1999 study of LGG’s ability to prevent or lessen antibiotic-associated diarrhea in children found that 26 percent who took placebo had diarrhea, compared with 8 percent who took LGG
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A 2000 study involving 287 youngsters from 10 countries found that LGG reduced infectious diarrhea by a day compared with placebo.

Then about 10 years ago Culturelle stopped working for me. That was when I saw new ingredients that were not listed on the old labels. As indicated in my signature, I learned the hard way that some of these “other ingredients” shred my gut. I now also avoid VSL#3 and Align for the same reason. VSL#3 used to help me a lot.

Other ingredients in Culturelle: Hydroxypropyl methylcellulose, sucrose‡, maltodextrin, sodium ascorbate, magnesium stearate, titanium dioxide (color) and silicon dioxide.