Unlicensed tattoo artists often work from their homes, sometimes offering customers designs for little more than a tenner.
But if they are not sterilising equipment properly, the real cost could be much greater.
Blood borne infections such as Hepatitis B or C and HIV can be transmitted through contaminated needles, and the symptoms can remain hidden for years.
Even if it is not that serious, painful infections can scar the skin.
Unregistered tattooists, or scratchers, are hard to trace, so Hartlepool Council has become the first in the country to introduce hygiene rating systems for tattoo studios.
They hope that by promoting the legitimate businesses, they will raise awareness of the risks, and let customers know where they can go to be safe.
Kez Hill's studio Intravenous Ink got the highest rating - level 4 - after the first inspection of the equipment, inks and needles that she uses.
The other tattoo studios in the town to receive top marks are Wishful Inkin, Spy Monkey and CopesStudios.
Environmental health officers came to the premises on a surprise visit to check how Kez was running the business.
The scheme is voluntary but four of the six studios in Hartlepool have already signed up.
For them, it is good for business. For their customers, it means they will be confident that when the tattoo machine is switched off, the result is what they were expecting.