Originally Posted by bigtopsfinn
Like previously stated, ask the person selling it.
I'd say that resin, trichomes, color, smell, etc. do not always contribute to the quality. Some of the most potent weed I have ever smoked, looked and smelled comparable to mid-grade...
Also cannabis affects different people in different ways, so while one strain might be a good pain-reliever for some, it may not be for others.
Even if you do find the perfect strain, it's also not a guarantee that the weed you are buying next time, although with the same strain name, is actually the same all the time. The cannabis industry is unfortunately very unregulated. There is always someone trying to make a buck, even if it means alienating other people's (breeders') hard work.