One thing that happens with any product that's made to market at a relatively inexpensive price point is, the quality control standards are lowered. So, out of a carton of say, 50 of an item, there can be some real dogs, some not so good, and a few quite good.
Hence, one guy says brand X low price stuff is really terrific (he got one of the good ones) and a lot of other people say the same brand X is garbage (they didn't get the good one).
I believe some of Cabela's high end optics are made by Meopta, a European company, not very well known here.
There are ways to objectively test optics, but, not something that's generally done at home- the testing equipment is expensive. Modulation Transfer Function testers are used. For what MTF is, go here:
http://photo.net/learn/optics/mtf/
MTF machines can objectively test the resolution and contrast of any optical device.
Another way, that you can do at home, is with Air Force test targets. Those are somewhat like the eyecharts at your opthalmologists office, modified for use with optics. You can compare 2 (or more) different optics by pointing them both at AF test targets and comparing.
However, neither method does anything to test for durability- a factor in riflescopes.