Have you heard of Next Door? If not, it's a forum specific to your neighborhood where neighbors can post questions or advice. I would suggest signing up for Next Door in your new neighborhood and asking around for the recommended carpet cleaners in your town/city, or even any house cleaners that people work with.

Apparently all kinds of stains will turn up under a black light: Black LIght

Black lights detect items that contain fluorescers within them when the UV rays from the light shine on them. Some of the spills a person might find with a black light include:

• Biological stains: saliva, semen, urine and blood
• Laundry stains: dried liquid detergents
• Club soda and all liquids containing quinine
• Invisible ink made from lemon juice or similar compounds
• Toothpaste with whiteners that fluoresce

If the carpeting looks clean and doesn't have an odor, ripping it out may be overkill.