According to the Sims Wiki, "The salon is the workplace for the Stylist profession in The Sims 3: Ambitions. There, stylists can give makeovers to their clients, there is also a tattoo chair to make tattoos.
There is a glitch with Sunset Valley's salon which resets your Sim's age. Some people believe this only happens if you have a tattoo done, but it is if you visit the salon in Sunset Valley and it puts your age to the beginning of the current lifestage."
World: Appaloosa Plains
Name: Shear Perfection Salon & Tattoo Parlor
Size: 30 x 20
Cost: N/A
Name: Barney’s Salon and Tattoo
Size: 30 x 20, 30 x 20, 20 x 30, 25 x 30, 30 x 20, 21 x 30
Cost: N/A
Note: Auto places when Ambitions is installed.
World: Twinbrook
Name: Drea's Salon and Tattoo
Size: 20 x 30
Cost: N/A
Which is your favorite Salon?
