Is there a problem with defrosting meat on the counter?

The problem with defrosting meat on the counter is the temperature the exterior of the meat reaches, and the duration it stays there in order for the entire thing to be completely defrosted.

For any meat, unless you're letting it reach room temperature from a refrigerated temperature (35-40℉) to immediately cook it you should keep it at a refrigerated temperature to inhibit the growth of beasties.

The bottom line is that above 40℉ things will grow. With a steak defrosting in the refrigerator you are assured that no part of the steak gets above 40℉. If defrosting on your counter the surface temperature of your meat likely gets at least as high as 60℉ before the entire thing is defrosted.

The only time my meat is exposed to temperatures above 40℉ is during transit from the store, and if I'm letting it get to room temperature for immediate cooking (30-60 mins).

I will occasionally "rapidly" defrost things under cold running water in the sink. I recommend against still water because it will reach room temperature and the previous warnings will apply. The running water speeds up the heat transfer. Keep in mind though that this uses an insane amount of water and is still pretty slow. I usually only bother with tuna steaks. I can get a 1" thick tuna steak defrosted in about 25 minutes this way. Make sure that the meat is in a water-tight zip-loc bag.

Please see the USDA's safe defrosting methods for additional details. The only methods listed are refrigerator, microwave, and cold water method.

Technically or practically?

Technically, it's not the best idea. The purpose of thawing is to bring the meat above 32 degrees but not above 40. (Bringing it to room temperature is a separate process, done only immediately prior to cooking). In a refrigerator, the temperature is probably between 35-45 degrees, so there's no problem. On the counter, ambient temp is between 65-85, so it's dicey-town bacterially. 40-140 degrees is the "hot zone": good for bacteria, bad for you.

The particular danger of thawing on a countertop is that the exterior of the packaging, especially juices on the surface of the meat or on the inside of the container, may reach room temperature and remain there for hours. So, ideally, using the refrigerator overnight is best.

...On the other hand, lots of people do it. Defrosting outside of the fridge is much faster, and you're probably fine as long as you don't let the meat sit out once it's center is thawed. It would also be wise to use the meat that day, so that any bacteria which may have started working while it sat out doesn't have too long to mingle (especially if your fridge isn't a very cold one).

The key is that you're going to cook this meat, so its exterior will be flash-fried, steamed, or seared at well above bacteria-killing temperature.

Your best bet is to use good meats, wash your hands, and be mindful of contaminating cutlery and cutting surfaces with raw meat juice. Otherwise... it hasn't killed you yet.

The Food Standards Agency say that it is only safe to defrost items at room temperature, when they're not going to be cooked before eating (such as cheesecake). Meat would not fall into this category, so would be safer to defrost in a fridge (typically for 24 hours, but depends on size/etc) or using a defrost setting on a Microwave.

It it's not for immediate cooking, defrost in the fridge. The rule of thumb is for a piece of meat to spend no more than 4 hours (cumulative) in the danger zone (above 40 degrees F). A thin piece of steak won't take that long to defrost, so it's relatively safe to defrost on the counter and then cook immediately. A big roast or chicken on the other hand, has a much higher mass to surface area ratio and will take longer to thaw, leaving the exterior in the danger zone for longer than is safe.

If you want faster defrosting, put the whole sealed package of meat in cold water in the fridge. Water is a much better conductor of heat than air, so it will speed up the process while remaining under 40 degrees. I think you could also combine this with brining by taking the meat out of its package and adding sufficient salt to the water (about a tablespoon per cup).

Personally, I like to put the meat in a marinade (with salt and acid) in a gallon ziplock bag, and stick it in the fridge for a few hours.

No no no no. Bag idea. Don't defrost on the counter. Like a lot of people said already, 40-100 degrees exponentially causes bacteria growth. Yes proper cooking can kill a lot of bacteria, but nothing is guaranteed. Besides, certain types of toxins (eg spores) are produced by bacteria and aren't destroyed by heat, only way to prevent is to not allow the growth of the pathogen.

Either A) defrost the day or two before in the fridge ( change the liquid). The safest method. B) defrost in a ziplock bag in the sink. Restaurants do this ALL the time. Meat defrosts fairly fast. Use cold water to defrost, not hot ( same bacteria problem, plus paially cooks meat, yuck). Just leave the sink barely running with cool / lukewarm water. it will be defrosted in 30-60 min.

C) microwave. Which is fairly safe, but can destroy a good cut of meat. Not preferred

A lot of food poisonings are caused by this. Ever get an upset stomach?

thaw meat in cold water while in a ziplock bag, check on the water every 30 minutes make sure that it stays cold

I remember my mother defrosting most meat from the freezer on the counter. She would take it out when she came home from work for lunch, and it would be ready to cook when she got home. We never got sick. But that was almost 50 years ago when bacteria wasn't as prevalent or resistant as it is today. Greed and selfishness in the forms of people not being responsible enough to consider others... By not washing their hands, not cleaning up after themselves, littering, etc. It's kind of sad.

I now buy very little meat and when I do, it's strictly organic, grass fed humanely raised local meat. I defrost it in the refrigerator only.

I am sorry but I have been defrosting boneless chicken breast for at least 4 years ,on the counter and cook it to 160 degrees and have never had a problem (maybe I've been lucky) but my chicken is so tender and have never been sick, ???

I defrost chicken breast meat with a sous vide circulator set at 160, putting the breast in once the water is at that temp. It takes a very short time to regain the set temp once the meat is introduced. After meat and water has reached 160 and been there for a half hour I start my cook time of two hours. Excellent results.