Quite a lot of bacteria show up on the throat swab culture. Most of them belong in your throat normally. What the lab tech has to do is pick out something that looks abnormal. Not very many organisms can actually be identified in this way. And a lot of it depends on the skill of the lab tech. Then the doctor has to figure out if that tentative identification matches your symptoms.
Of the organisms that usually cause throat infections, Streptococcus and Candida stand out in these cultures because they make a dramatic color change on the petri dish and/or they have a distinctive shape under the microscope.
The organisms that cause things like Gonorrhea, Diptheria and Whooping Cough will also show up, but to positively identify them takes further tests. If you aren't showing symptoms for those diseases, they probably won't do the test.
Anyway, the value is kind of iffy. When we do this test in class, about 5 to 10 percent of healthy students have a positive throat swab for hemolytic strep, so it's hard to say what the test even means. In the 90's the medical center that I went to would always hand out antibiotics without testing, so I started checking my own throat swab when I was sick. If I had a positive test, then I'd go get some antibiotics.
More recently, I had a weird case of thrush and the doctor had some smears done. A couple of days later, I received a phone call saying they'd lost my sample and could I come give another. Then another call saying, "never mind - it's negative." Suspicious, I went out to the lab and did my own damn smear. It was positive. I took color photos and took them to the doctor and got treated. The lab still billed my insurance $400 for ten minutes work that they didn't even do, then lied about.