There are also some carriers out there, that although not life threatening, are not good for your baby! Any carrier that allows your baby's legs to dangle straight down is not a good carrier. This is bad for both their hips and spine. And even though you think your baby enjoys being able to look out at his/her surroundings, your baby should never face out in your carrier. This is also very bad for baby's back and hips, and can cause over-stimulation. Here's a link with explanations of the actual physical harm it is causing.
These two types of carriers, bag-like slings and "crotch danglers," make up a very small percentage of the options available. They are simply two of the cheapest, most widely available options, which sadly means they are everywhere.
This blog has a ton of information about the pros and cons of each type of carrier. It also lists the brands to buy and the brands to avoid, for quality, safety, and comfort. It's a great reference for anyone interested in babywearing. I refer to it frequently.
I'm ashamed to say that we used a "crotch dangler" AND we faced McKaleigh outward. Thankfully, not frequently, we only used it a handful of times. A majority of our babywearing was done in a homemade stretchy wrap, and facing outward wasn't something I did often. But still, we did it, and it's because, unless you seek out the information, it's not readily available. Companies that make these poorly made carriers actually show babies being worn facing out, so how is any parent supposed to know the damage it can cause your child? Isn't it sad that companies that make and sell these baby items are so poorly educated on the items they are selling?
Also, unless you've done thorough research and actually know what you're talking about, don't try to tell someone that wearing their baby is dangerous. It is not! I don't know how many stories I've heard recently, of mamas safely wearing their babies being hassled because of all the fuss in the news. It is always by people who have no clue what they are even talking about and have likely never worn a baby.
So once again, babywearing IS NOT dangerous. Bad carriers are.