The only examples of tattoos to the scalp before this past year have been tattoos to the scars. I was not impressed at all with any of them. They were not the SMP technique of creating the "dots" to mimic hair stubbles. They were aweful, to be frank. The ink faded and ran like veins while turning color within the scar tissue.
The idea of putting dots all over the head is new and have seen few cases in person now. I've seen few decent cases and one horrible case. The ones that I think help to create the illusion of density are the patients who have diffused thinning. The patients who had this done said they were happy with the procedure, however, I have to admit that I was a little surpised at how quickly the ink faded in short period of time (3-6 mos). These patients kept their hairs long. Between 3-6 months, the ink had not turned blue'sh. I can't say what they look like now as I have not kept up with their progress.
The horrible example I saw was of a guy who had a very small ht procedure about 10-15 years ago in a near by state. He's currently a NW6. He shaves his head without a guard every few days. He wrote to Dr. Ron stating he had the SMP done to his scalp a year ago and was at his wits end. The clinc where he had it done initially said the work looked good (2 weeks after). He was shocked that the black color had changed to blue almost right away. His profession does not allow him to cover his head. His hair looked very unnatural whether he grew his hair long or shaved it. His co-workers were brutal. After calling his smp clinic a few times, they finally agreed that his head was blue and paid for him to get the smp lasered off. We saw him after one laser treatment, it was still noticeably blue. After 4 laser removal treatments, it starting to look better.
I would recommend that if you decide to go this route, do so in a small test area or know full well that you may have to have it lasered off. I personally would not recommend smp unless you're out of other options due to risk of color changing.