Only if enough people have reasonable doubt.
For example, if I were to claim something like Eternal Engine m1 2:38.99, that time would be accepted without much question. People know that the record has been mine ever since last September, I've touted 2:37 as "a definite possibility", and while I don't feel a need to play that level anymore, that's something they wouldn't know.
Now suppose some random player joins and immediately claims a 2:34. Besides the 40% chance that we can prove a lie immediately, that player would have to know exactly what he's talking about, and make every attempt to provide a video or at least a picture of the victory screen.