They do work, just not well enough to be useful for scanning. I have a handheld infrared SLAM scanner, and when it encounters moderately reflective or dark surfaces, it interprets them as voids because they absorb or scatter the IR. Anything translucent or refractive is similarly a nonstarter. The surfaces it does scan are not very accurate (covered in slight bumps from inaccuracies). This means it can't scan most objects, and the ones it can scan still require a ton of cleanup.