TF, this is not intended as “talking down to you”, as you have some electronics knowledge. But, other readers do not, so I’m writing this for a wide range of readers.
You said the bulbs run hot. Were you able to measure how hot, and were the bulbs in enclosed or confined fixtures? (Only those stated to be rated for such use will hold up in that usage. That requires efficient LED’s & power supplies, or lots of heat sinking, or high temperature components. However, high temp supply components don’t help if the LED itself gets too hot internally. Lots of heat sinking is also very limited in how much it helps, unless it conducts the heat to exposed metal fixture parts reasonably efficiently. Otherwise an enclosed fixture tends to trap the heat anyway, and the main gain from the “big” heat sink is thermal lag — it takes a few seconds longer to heat up.)
Outside of that, my guesses would be, in order:
1) Inadequate heat sinking. (Just because a heat sink looks adequate doesn’t mean it is. The mfgr. may have skimped on good thermal transfer from the LED into the heat sink.)
2) Inefficient AC - to - DC conversion in the internal power supply (combined with insufficient heat sinking of the supply that might be ok with a more efficient LED). This is essentially your “crappy design”. This can be overcome in some cases with enough heat sinking, but it should show up in the energy use rating. “Should” You’d need a power use monitor or a good digital multimeter to be sure. Chinese “watts” sometimes seem to have their own definition - whatever looks best on the box or in the advertising, that they think they can get away with...
3) Inefficient LED (which again can be overcome in some cases with enough heat sinking, but that should also show up in the energy use rating. See “2” above.)
4)Poor internal electrical connections. The Chinese are really bad about this, in all manner of products.
5) Crappy parts substituted in production. Again, the Chinese can be really bad about this.
6) It actually IS remotely possible that the incoming AC could have HF content, if you’ve not looked at it on a o’scope. Strangely enough, if there’s a circuit to suppress intermittent incoming crap (a good thing to include, to protect the fragile electronics including the LED), it could well be overworked and heat up if hit with continuous incoming HF content. Such content, intermittent or continual, unless intermittent AND extreme enough to cause detectable flicker, would not bother an incandescent in the least. However, I’d think a problem with excessive HF content in the supply might show up in other of your electronics, too.
My experience with LED bulbs, carefully used, has been fairly good. So far, it’s been better than CFL’s, that’s for sure. As long as the color temperature is 3000K or below, and as long as the “frosting” / diffusion is good, glare is not a problem. I do have some 3’ and 4’ LED bulbs that are “glary” — too much light from too small (or too narrow) a source.
Failures have been few, so far, though I keep wondering about problems with lightning, which took out quite a few fluorescent electronic ballasts for me over the years. However, I’ve used very few LED bulbs in enclosed fixtures, and always check for that rating for that usage. (If it doesn’t say, it almost certainly isn’t.)
The most obvious seemingly very premature failures I have had were with 4/$4.99 100 watt-equivalent bulbs made by an outfit named Zilotech. (Yeah, I know...) I should measure the power consumption of a still good one, running temperature, and weigh one: I am almost certain they skimped on the heat sinking. Still, neither that failed abruptly and completely quit. Instead, they became intermittent (on and off), pointing to an internal connection issue, I would think. I’ve also had a 40 watt-equivalent Great Value bulb go intermittent, and a couple 60 watt-equivalent Great Value bulbs quit abruptly and totally. The GV’s were all older bulbs roughly 1/2 way into their 7-yr, IIRC, rated lives, which is not that bad, IMO, as transients are still a possibility. (We get lots of t-storms and close lightning here, among other sources of “spikes”.)
LEDS save us almost nothing in the winter, but in the summer they save us at least $20 a month vs. incandescents. Sometimes more.
“7-years” @ 3 hours a day, I should specify...
The base of the bulb was hot enough you did not want to hold it. The LED's were still operating when I removed it and found it very hot. Heat means power consumption. LED's themselves don't get that warm. I even cut the plastic bulb housing and examined a failed unit. I am sure the LED's are still operational but the power supply failed. I've built many types of power supplies. I have held an Extra Amateur Radio license for many years and hold a GROL commercial License. I spent many years building scratch electronic devices. Have etched and build many PC boards from scratch.
None of the failed bulbs were in enclosed fixtures. Some of the bulbs were mounted on top of the fixture and some on the bottom of the fixture (hanging down). All were open on top or bottom of the fixture.