The problem is simple. It's easy to cheaply make a good looking scope on the outside, even make some pretty good optics in normal light, while concealing poor materials and workmanship inside the tube. They often work fair on a .22 rifle, or a co2 pellet gun, but put them on a Springer and your shots go all over the place. Sooner or later something will come all the way loose and the scope is toast. Gun writers for the popular gun mags are only too willing to give glowing reviews to just about anything for sale, and it looks good on the outside right, so lets give it a try.
Variables are the absolute worst.
There are so many precise moving parts in them that there is no way to make one at a low cost. Point of impact will vary with magnification, and likely shift at a single magnification. Optics will be bad. If you are tempted to buy one anyway, just send one half of the money to me instead. I don't have any advice for this type scope, as I have never used them.