[Uncle Bulgaria]

So, the consensus is that there is none.

I have a lot of these reddish ones among treasures in a set of drawers sold to me by whiskas of this parish. It seems (I mostly dabble in audio, though the small values will probably come in handy in radio repairs) that I can use them with impunity going by the value alone. I've enjoyed what I've read of 'The Art of Electronics' though much goes over my head, and I think in the undemanding audio field (compared to gigahertz propagation) the difference between 'excellent' and 'good' will be moot.