Up until the last decade or so, just about any facet of tattooing came with a literal stamp of indelibility. Once the mark was there, it was there for life. Although there have been many advances made in regards to adjusting or fixing the appearance of a tattoo, there are still some problems that are so intensive or complicated that they tend to be the sort of things that you would rather not happen in the first place. After all, trying to fix or adjust a tattoo is literally a pain.
The phrase "healing out" refers to the loss of color from the surface of a tattoo. This happens most often in conjunction with the initial healing, and appears as white or blank spots in the design. Poor aftercare or problems with healing can cause this, but so can a tattoo artist with poor skills. "Homemade" tattoos are often too shallow and suffer from this problem a lot. This is one of the easier problems to resolve, as a touch-up session or tattooing over the missing spots again tend to put them right rather directly.
Skin is a living fabric when you think about it. It can stretch, breathe and has processes going to clean and repair itself. It doesn't have a weave like most man-made fabrics, and to be honest, it very closely resembles meat, in that it does have a grain, or structure. Either by genetic predisposition, or due to some poor skills on the part of the tattoo artist, some people wind up developing scars on their tattoos. The first one I ever saw was the outside line of a bass clef tattoo on the upper arm of a guy I knew in college. He said that artist tattooed the line in one strong pass, and it felt like he was being cut. It turns out, that really was an accurate description of the trauma his arm suffered, and that one line formed a strong, raised scar when it healed. This type of side effect is not one that can be fixed without plastic surgery treatments, and those will wind up destroying more of the tattooing.
Sometimes you will see question on tattoo forums or message boards where someone is worried that their tattoo is leaking ink, or that it's spreading. This is called "blow out" and it's a result of bad skills on the part of the tattoo artist. If they are too heavy-handed or hold the tattoo machine at too slanted an angle, it's possible for them to tattoo the skin too deeply, which puts the ink deposit into a layer of skin where capillary action can move it around or where it can seep through body fat. This is not an easy side effect to fix. Sometimes the outline of the tattoo can be redone to minimize the appearance. Laser treatments might be able to break up the ink deposits that are outside the lines, making them less visible. But either way, it's not a quick or easy fix.