[cjensen]

There is also a safety concern with overly cheap tools.

For an example, the adjustable wrench in this article. What happens when you apply a lot of force on a stubborn nut? If the wrench experiences rapid unscheduled disassembly, you now have broken pieces flying in random directions.

In the US, the thing that most prevents this from being a problem is the threat of liability lawsuits. That doesn't apply to a tool made by a small company in China and sold by a fly-by-night outfit on Amazon's marketplace. I'm guessing Amazon is unknowingly the liable party here, but I'm not a lawyer.

[LeifCarrotson]

What's going to happen is that the nut will round over, because there's little in this design to prevent the jaw back-driving the helix. Having used a lot of adjustable wrenches, and rounded over quite a few bolts, now I keep sets of open-end wrenches in reach on the toolbench and for adjustables I carry exclusively Knipex Pliers Wrenches, which are awesome tools. There's no way you're breaking the casting of the wrench without a big cheater bar, which I admit to having used...while wearing safety glasses.

[sliken]

Knipex are awesome, a good example of quality resulting in a tool that lasts much longer than the cheap tools and causing much less damage to the nuts you are working on.

[xd]

Biggest worry would be smashing your knuckles on something when it gives up not the thing exploding.