I've had dogs for the better part of my life and not a single time was a 'foxtail' an issue, whereas grasses that grow these kind of constructs are pretty common around here. Did I (and my dogs!) get lucky? How common are these issues?
The main issue we've found is she gets them stuck under her "armpits" and under the tail. Places that make them very difficult to find. Even more insidious is when they embed themselves in the harness, only to make an appearance weeks or months later when the outdoor foxtails have mostly been cut down.
The problem is that they can work their way under the skin with a barbed spike that is one-way only. So if they get deep enough the only remedy is to cut the skin with a scalpel - by the vet of course.