It is not as common as you would think. People who deal with it are much more likely to post about it than people who don't because it is a non-issue for them. I have never felt the need, for example, to post that none of my current Greyhounds or any of my Ibizans have this issue.
I agree with Krissy. No dog is perfect. Even my "practically perfect" dog can have a bad day and be in a grumpy mood. My recommendation would be to evaluate what you can and cannot handle and find a dog that has been fostered long-term. I had several hang out 6 months or so. Bounces might be an option as well. Dogs can act differently in different situations, but you get an idea of basic temperament and personality. I had one who was a holy terror in my home. She hated being in a pack. Once she was a single dog she was really good. I've also had dogs that hated being solo and acted out come into my pack and thrived. Their core temperament obviously did not change but their behavior did. Dogs can be sweet and amiable until they have a resource to guard, so don't think a dog with these concerns is a contradiction. My worst space and sleep issue dog excelled with people and worked Renaissance Festivals with literally thousands of patrons to interact with. I just removed him from the crowded areas and set him up for success when he needed to lie down and rest.
Out of the around 100 Greyhounds I have had come through my doors, we've had 9 that had either sleep startle or space issues. Only one might have bitten if not given proper berth. The others just complained loudly and bared teeth. Other than being loud and annoying it wasn't an issue.