Dimmable LED bulbs have active circuits in them to convert the A/C input power to DC power to light the LED.
Dimmer switches turn the power on and off 120 times a second.
Things are getting better as both technologies mature however there are still come combinations of dimmer switch and dimmable LEDs that don't work well together.
IMHO the best way to determine if you flickering, dimming, never going off (just really low level) etc is caused by an incompatibility is to temporarily install an incandescent bulb.
If the dimmer works well with the incandescent
and the LED bulb works well in a non dimmer location,
then the two are not compatible.
This is probably lighting 101 for most folks. I only created this post to maybe remind people to not discard their last incandescent bulb.
I got rid of my last incandescent bulb 4-5 years ago, during a CFL binge. Then a LED Binge came along. It's possible I have an incognito bulb somewhere, in a junk box. Maybe it looks like an early CFL and it's actually a disguised Incandescent.
I kept all my old incandescent bulbs when I moved everything to LED… I have a couple boxes of them… Will have to do something with them at some point.
It's not like incandescent bulbs are impossible to get, you just need to get a decorative or otherwise specialty bulb. They're still readily available at every hardware store.
The vast majority of incandescent bulbs that were sold in the USA were standard A19 frosted white bulbs. These are gone.
These days, it is even becoming much more difficult to find a ceiling light fixture that has a screw-in style base for bulbs. Most at Home Depot have LEDs built into them. So when they fail, the fixture is pretty much trash.
This is my biggest pet peeve. Or ceiling fans that take those stupid miniature base bulbs. Sure they did it so you couldn't put a 100w incandescent in there, but I can still put a brighter LED in if it was a standard base.
This is the only reason I have a few Ikea smart bulbs. They were the only MFR of smart bulbs that I could find with candelabra bases. Since they wired the switch to control both the power to the fan and the lights (no separate wire at the fixture), I was pretty much stuck with smart bulbs instead of switches on three fixtures unless I wanted to dig into running new wiring.
I took a hammer to the last remaining 8 foot fluorescent lamps yesterday. I do have many incandescent lamps which I save for special applications. The 135 watt Durotest lamps make great heat lamps to keep our shared well from freezing in the winter. I have destroyed most of the CFL lamps I used before LEDs.
I recall back in the 70s on a commercial job laborers busted thousands of fluorescent lamps directly into a dumpster. Long before we realised we would all die early because of it.
Actually, used to be on a mercury spill team and had loads of training and actual experience in cleanup. It takes 0.1 mg/m3 of mercury in air to be an OSHA reportable spill. The recommended limit is half of that. In order to reach the OSHA limit would equate to a spill of about 2 ounces of mercury (a drop about the size of a quarter, or 56 grams) in an enclosed space. This is on the low end of toxicity and is based on an Permissive Exposure Limit (PEL) for an 8 hour day and years of exposure.
The typical bulb has ~ 5mg each. So, it would take a little more than 11,000 bulbs in an enclosed space to create enough vapors to cause a spill that would require OSHA to step in. Even then, it would require that the individual be exposed to it for years before it caused any issues. To reach the lower recomended exposure limit would still require more than 6500 bulbs.
The warnings on bulbs came about to prevent indiscriminate disposal that could aggregate in the grounds in/around landfills and disposal sites. If EVERYONE did this, it would create a problem. I would be more worried about the mercury in thermometers (yes they are still around) or in the blood pressure manometer on the wall at your doctors office if he still has one. (Mine does). Both of these actually contain enough mercury to be considered a major spill on their own if broken or incorrectly disposed of. Additionally, I have personally seen many of these with hairline cracks that were contaminating the air in the work spaces they were used in.
Here's something even worse than broken lamps. I recall as a kid at school someone brought in a vial of mercury (probably came from a thermostat) and deliberately spilled it on the floor. Then we did something to make it run around - perhaps with magnets. I can't recall that part. And here I am, having been in contact with mercury many times, and made it to 80 years old! Plus my mom used to take my temperature with a thermometer that contained mercury.
When I was a kid, my Dad had a huge jar of mercury, it must have been nearly a pint of what he had collected over the years. I think he saved it from thermometers, thermostats, and car trunk/hood lamps.
It was so fun to play with, it was heavy and pretty cool to stick your hand in the stuff and feel your hand float in it. You could squish it in your palm and watch the beads then it would reform into a bigger drop if you cupped your hand.
I don't think I suffered any ill effects from it, but hard to say. It was a neat experience I will never forget.
Largest mercury (better name - Quicksilver!) mine in the world was in Almaden, CA. Yes, same Almaden as on the winery from that area...how's that for a scary combo - "Would you like some Quicksilver with your wine madame?". If you're ever in the area, there is a very nice museum that is fun to visit. Take the kids, get them a Quicksilver soda and they'll quiet right down.
We played w/mercury one day when I was in elementary school - IIRC our teacher had some and decided to share it with us. We were passing the stuff around to each other, playing w/it on our desks, etc. They just don't have fun days w/toxic chemicals at school like they used to.
Oh we've wondered quite a lot, actually. Thanks for explaining everything...
If you're ever in the area, there is a 
