I used to be a Disability Examiner. It would be highly unlikely anyone could fake it--rarely, people improve over many years. You have to be in pretty bad shape to get SSI/SSDI or in moderately bad shape and pretty darn old. The stat I've heard is 1 out of 3 are approved initially, and 1/2 get approved eventually (usually at ALJ level, which takes at least a year and usually longer). I wish you well.