Cheap binos CAN have a range of problems. Zoom binos have already been mentioned as over problematic. Inexpensive binos can have an exceedingly narrow field of view. The optics can be mismatched so to give a distorted image, normally really only noticed at night with point sources of light on a black background. This can be terrible chromatic aberration, field curvature, astigmatism, pin-cushion, etc. Just as bad is a set that won't give a single image, but double, and there is no way to adjust the optics.
But, there can also be gems within this lot.
Also mentioned is the stability problems with high magnification. Sure, these binos can be mounted onto a tripod for a more stable platform, but high magnification also means a narrower true field of view, and a smaller exit pupil. One aspect in astronomy that binos excel in is as rich field scopes. This means binos that have a large exit pupil to very close to the maximum the human eye can open to. The advantage here is it maximizes the total amount of dim light that an extended object has into a very condensed space. It is the only way many objects can be seen easily, and even without filters. So much so, that there are some objects that are just about totally invisible in telescopes are actually visible in binos that are smaller in aperture. This is why the quintessential astro binos are the 7X50. These have an exit pupil of a tick over 7mm, the largest human pupils can open.
This was the ultimate factor that swayed me to selecting the 11X70 binos I got. 70mm is plenty of aperture grunt. 11X makes them also usable for terrestrial use, and the 70mm aperture is lighter to handle than 80mm for this too. This set also gives an exit pupil of 6.4mm (70 / 11), which for my older eyes is a better match. The pair I got also has a healthy 4.5deg true field of view, which is great for both astro and terrestrial use (I really love this wide field of view,
).
Bonus was they were the inexpensive Andrews Communications branded set,
. Not the cheapest, but not the most expensive either. These binos can also be individually collimated to give a single image, which I've had to do (binos get knocked about with life and the optics shift, but easy to adjust with this set). I am very happy with the optical performance of this set too. I'm sure there are binos that can give a better image, but I feel I've got one of the 'gems' I mentioned earlier.
Now, you need to understand the strengths and weaknesses of binos, the potential pit falls of cheapies, the potential quality of more expensive sets, and what best suits your requirements. I'm happy with my set, but it is not an absolute product endorsement. They suit me for the reason I detailed, nothing more.
Food for thought.
Mental.