In the world of fixed gear components, there are a few levels of quality. Top tier components are those which were designed for professional track racing, for example Sugino 75 cranks. Below those are components which could be used for track racing, but are more than likely to end up on a high end tarckx bike, for example red anodized Sugino 75 cranks. And below those are components which are brightly colored, not intended for track racing, are 100% likely to end up on someones color coded tarckx bike, like anodized All City/Messenger/Origin8/Soma/Iro/Bulletproof/Eightinch cranks.
These are usually the same Taiwanese crap with different branding, if you look at some of these the only difference is the brand stamp on them.
Bottom level components usually work fine, sure your cog or chainring is shaped more like an oval than a circle, or the threads on your hubs or cranks strips whatever you put on there, or your chain snaps when you're pedaling downhill, but the point is they're functional. The people who buy them generally care more that they're colored antifreeze green than the fact that what they're riding is poor quality.
Generally, these are imitation products. A few years back, the rim to have was the Velocity deep V. A number of months later, Weinmann DP18s came out in full force in all colors of the rainbow.
Imitation products sort of de-value the original brand, especially if they become more widely distributed. Again, why spend $75 on a Velocity Deep V rim when you could get a complete Weinmann DP18 wheel for that amount? Things like weight and quality control don't concern most people who buy these things. For most of them, a color coordinated "fixie" is their first bike. And for a lot of boutique type track bike shops, this is where a lot of money is made.
If any of you ever check Denver Craigslist, you are well aware of the guy that has a bike shop of some sort and tries to sell products from it through online free classifieds. (This is prohibited, you should flag his posts) It was through this guy, however, that I learned of the existence of knockoff B43s. The Weinmann DP41.
Lets not talk about how the B43 came out after the H+Son Formation Face, the two are distinctly different (besides H+Son wasn't the first 4cm deep rim, think Gipiemme Tecnos and Campagnolo Shamals), but instead think about how this guy, selling shitty Taiwanese components and promoting his shop through free online classifieds instead of traditional advertising hurts more legit Denver bike shops like Track Shack. Its kinda sleazy. Especially when you write things like "I CAN TAKE CREDIT CARDS" in your ad.
But hell, if you don't care about quality or any of the associated benefits, and want 4cm deep rims, go for it.