Sometime last year I was buying parts for a project and decided to purchase a grab bag of ceramic capacitors thinking that it wouldn’t be any big deal to dig though them and turn them into a useful assortment of parts. There are a few logical breakdowns here:
When you buy the “grab bag” you’re really buying a bag of about 20 values of capacitor, in a really disorganized bag which renders the bulk of what you’ve got useless. So it comes down to you really just need a 47uF capacitor, and you’ll never find one because there isn’t one in there
They take forever to sort and even when you’re done you just have a slightly more organized 6 piles of random component values instead of one huge pile!
Finally, there’s probably a reason they ended their lives as “grab bag” capacitors – in this case a lot of the components look like they’d gotten stuck somewhere in a piece of equipment, they were all roughed up and missing chunks of ceramic, hardly something you can identify much less feel good about using.