What are the bad things about tattoos?

If you're allergic to the ink, you'll know within the first few minutes of getting tattooed. I don't know of any serious allergic reactions associated with tattoo ink but it's certainly a question to bring up ahead of time. I'm guessing it's just really irritating and itchy. I'm also guessing there's an alternative ink that can be used.

If the tattoo gets infected, it can compromise the design but again, i have never heard of a serious complication resulting from a tattoo infection. Theoretically, gangrene is possible but you'd be an idiot to let an infection go that far in this day and age. Keep the tattoo clean and use pure soap and lotion and you'll be fine.

Other risks are social in nature.

Depending on the location of your tattoo and its content, the ol' job search might become a newly political experience for you. Some places just will not hire bad asses for some reason but happily, with the burgeoning fashionability of tattoos, the prejudices against them are beginning to fade. Much like Grandpa's unmentionable Navy Lady.

You might regret your choice of design afterwards. This is why a tattoo should NEVER be an impulse buy. Besides, you probably won't get a walk-in appointment anyway.

It might end up being more expensive than you had expected. Some tattoo places will agree to a payment plan for very large pieces like sleeves and back pieces, but don't count on it and ask beforehand.