Sorry for the late reply @rocketqueen, I stopped getting email notifications from this thread a while ago and can't figure out why. I will never, as a professional, quote 100% tattoo removal. My idea of 100% is different from yours, and it's not a tangible thing to fight over. Even in my "best case" scenarios, I can still find trace amounts of pigment if I look hard enough. A casual stranger who didn't know the history, wouldn't know though.
Also bear in mind, "dedicated to treatment course" isn't always a factor in how successful any given removal will be. How the tattoo was done (scarring, over worked area, dragging or barbed needles, etc.), pigment used, pigment saturation, liner vs. shader, location on the body, immune system, age, age of tattoo and quality of life will all play roles in how much any given tattoo will be functionally able to be removed. There is no black and white answer with tattoo removal.
Not some lasers, all lasers used for tattoo removal have the possibility of white ink turning black. In fact, many colors shift during removal. Black ink will often fade to brown or sometimes if it's got a deep indigo blue, that starts to show after a few sessions. There is no MSDS for tattoo ink, without knowing the ingredients there's always a possibility of color shift. Moreover, even if we do know the ingredients, there likely hasn't been any long term studies done on the effects caused from exposure to lasers.
To directly answer the question, it doesn't disqualify someone but it does cause for a very serious conversation about realistic expectations in my office.
Please understand that my job is to create very realistic expectations about what can and cannot be accomplished. The ol, "well my friend went here and they had the best and it's now gone after X treatments" simply holds no weight. Every tattoo done on every person is unique.