Really my last dance with Mary Jane? (warning: long read, but please help if you can)

The maturity of the fruit (bud) is only one possible reasons why the pot doesn't get ya high the same way. Whatever the case, for various reasons, including harvest time and curing and genetics and nutrients, they can all affect the type of high that a pot plant will produce.

I'm sure your predetermined mindset is playing a big role too.
Without the coke incident, you probably would have just thought that the dope you bought was bunk, like you said.

Different types of bud looks too different to be able to say if a particular kind is harvested well or not, or even to say if it's good without seeing it and trying it. I personally just judge if a bud is 'good' or not, based on what I like. If it's leafy, or dry or not sticky or stinky, it's probably not that good. Some kinds of pot are just different though.

The crystals you normally see are trichomes, basically it's little bubbles of THC.
Usually the more crystals you see and a nice amber color indicates good pot.
The hairs you see are usually white if the bud isn't mature. Red if it's too ripe.
White or yellow haired pot will usually be very cerebral. Red haired bud will usually be a very heavy stone. The best is when the hairs are nice and golden color.
Some kinds of bud is different, but most are like that. Sometimes the hairs are just green. Sometimes you don't see any.