Clinical tests have to be more reliable because they are designed by full-time research professionals and administered by trained people. Online tests may want to sell people something and they may be designed to flatter their target audience. These non-professional tests are how people claim IQ's in the 160+ range. If you mention an IQ score you need to be prepared to present a written report of all the sub-test measures to give the best evaluation result set.
This, in the case you score high on a few sub-tests, and you ought to include the far less flattering low test scores too, presenting documents which anyone can verify protects people from fraud. Another example of the duty to do this is claims of military service and medal awards. People deserve the right to be shown documents and invited to verify these documents from a DD 214 to, in the case of the Air Force, the address at Randolph Air Force Base records of medals awarded to protect everybody from stolen valor. The same applies to university degrees. I think universities will verify degrees claimed for free but they might charge a couple of dollars for copies of transcripts in case one suspects a transcript presented is counterfeit. Claiming the title of "Doctor" is a common practice of junk culture music stars who never went to graduate school, e.g. Hr. Watson, Mr. Dre, and Mr. Luke.
In short, backing yourself up with official reports protects people from fraud and we should do it.