10 random points in no particular order:
1. All HDMI cables are most definitely NOT the same.
2. For short runs, like around 3-6 feet, most cables should work fine for most usage, although a lot of the cheapest cables have really crappy build quality.
3. For long runs, ie. ~15 feet and over, you'll often come across cables that don't work consistently with some equipment.
4. Thus, don't buy cheap cables to put behind the wall. Often behind a wall you'll need 25 feet or more. If you cheap out there, you're in for potentially endless headaches in the future, and it's not easy to swap a cable behind drywall most of the time.
5. Crappy cables can give you snowy signal. In fact, it's one of the most common problems with crappy HDMI cables. Ironically,
this article sets out to convince us that all cables are the same, but then shows us examples of how they are actually not:
I've seen it myself with HDMI, although most of the time the "snow" is much less abundant than what you would get with poor analog signals. The "snow" is formed by digital artifacts.
6. Other problems I've seen are flashing, half-screen flashing, complete dropouts, and of course, the cable not working at all.
7. Average Monoprice cables are average... which means some of them are better than the cheapest cables on Amazon and eBay. Some of those cables really, really suck. The cheap Amazon and eBay cables are often about the same quality as the Dollar Store cables, but then again if you get a $3 Dollar Store 3-foot cable, it will most likely still work most of the time.
8. Higher end name brand cables often are better quality but usually they're way overpriced. A cheap cable might be $5, but a good cable doesn't have to be $200. For example, Monster Cable HDMI cables aren't actually bad cables. They just cost 10X too much, meaning they're bad for the price, but I'd rather have one of those than a $3 Dollarama cable... if someone gave it to me free that is.
9. In general thicker gauge is better, but not always. Plus, the thick gauge cables are often really stiff, which makes them annoying to use and route. Some of the best quality cables are better at the same gauge than other brands of cable at the same gauge. However, the best quality cables often cost way more, and sometimes it's easier to just get a thicker gauge to compensate... up to a point, when getting too thick a gauge makes them too stiff. For example, Dollarama cables are often 30 gauge, while many cheap (and effective) cables are 28 gauge, where some of the higher end cables are 24 gauge. 24 gauge is already stiff, but you can even 22 gauge cables from Monoprice which are super stiff.
10. Just because it works on your current equipment is no guarantee the same cable will work on future equipment. Individual components vary in their tolerance to withstand crappy signals. Also, what is considered standard today may not be standard tomorrow. eg. 1080p24 was the standard for the longest time, whereas some people may want 1080p120 for 3D some time later. 1080p120 is 5X the data of 1080p24. And 1080p60 should be considered a basic standard today.