Well, reading your blog, it sounds like you got a "cooked" puerh, which is normally the case these days. Musty, earthy are the types of characteristics that one would associate with a "cooked" puerh. I think I explained this somewhere in my blog too, although those things are awfully hard to use when you actually want to find useful information.
Basically, my understanding of raw vs cooked is this, and this is mostly information I've gathered in Hong Kong when I hang out at the tea shop with very experienced Puerh drinkers. They know their stuff. It really takes a lifetime to master.
Raw puerh is sort of how puerh is supposed to be, in its original, natural form, so to speak. Puerh's distinguishing feature is that it ferments after it is formed into shape, often in a cake or a brick shape. Over time, tihs tea ages, and the character and taste of the tea evolves. This would often take 15-30 years, and the more time it spends in this process, usually the better it will taste, assuming that it is kept properly, i.e. dry, away from sun, cool, and not in a location where it will absorb funny smells (putting it next to your perfume case, for example, might not be a good idea). In the old days, when the puerh firms in Yunnan province made tea the old fashioned way, they would make the cakes, leave it in storage for a certain period, and then they will sell it onto the market. It's a significant investment on the part of the firms to keep the cakes around for that long, but if you've been doing it for 30 years, that means every year you've got stock to release, so no problems.
If you buy raw puerh that is only a few years old, it will look like green tea, the tea is very astringent, sharp, brews a yellow/green liquor, smells strong, but not earthy. It is rather harsh, and is really not meant to be consumed yet. A proper raw puerh that is well aged should be some shade of brown. It is still somewhat astringent, but is much less sharp. The liquor should be brown in colour (the shades will vary depending on the age, the tea, and the amount of leaves you put in it). There will be some medicinal smell and taste, but as with wine, the tastes depends on how the tea has been aged and the quality of the original leaves. A properly kept puerh will taste different from a puerh that got slightly wet during storage, etc. This is where tasting experience and skills come in. This is also why well kept, well aged raw puerh is exorbitant (say, $2000+ USD for a cake of 350g). Part of that premium is in the variety and the changeability of the tea -- it really does change and has a very wide variety in taste.
Cooked puerh is how a lot of puerh made today is. Cooked puerh is basically raw puerh that got processed so that the fermentation took place at a much accelerated pace under artificial conditions. This includes, but is not limited to, putting it in a damp storage, sprinkling little bits of water over it, etc, to aid the fermentation. The tea ages faster, and becomes drinkable at an early stage. The problem is that the tea then becomes more or less fixed -- it will undergo no further fermentation, so it makes no difference whether you keep it around for 5 or 50 years. In fact, cooked puerh is meant for immediate consumption.
Cooked puerh brews a dark, pitch black almost, liquor. The taste is much weaker than the colour of the tea, and is rather mellow, with an earthy taste. There is a sweet aftertaste to it. There is no overall astringency -- the tea doesn't "cut" but instead "smooths". Some people prefer this taste. The tea leaves, when wet after brewing, should be pitch black. You can sometimes tell when a company mixes raw and cooked puerh together. The raw leaves are rather green, and the cooked leaves are pitch black. That's a mixed tea, which can be decent with age, although not of the top quality.
There's a lot of confusion over this, and I myself am no expert on this question either. Whiel nowadays I'm not too bad at distinguishing raw and cooked teas, when it's a really good cooked tea or a poor raw tea (poor usually due to original quality, or more likely, how it was kept) I get confused too. But for the most part, puerh you can get in the states sell cooked teas. Raw teas are generally very raw (under 5 years) and will look distinctly green. Those really shouldn't be drunk right now, although for experimentation sake you can buy a cake, and try it every few months to see if you taste any change.
That's a very concise version of it. I have described a few different kinds of puerh I've tried at various points in my blog. I really ought to take more pictures....