Photos can tell you quite a bit sometimes. Look for ones that are painfully old, poor copies, high rates of pixelation, phone screen shots, signs of editing... Generally, these can indicate there isn't a legit swinger connected with the account. However, some people are just rotten at media and it isn't a definite unless it's an obvious fauxpaus. A dead give away that always is entertaining is when they have pictures of different people who are supposed to be the same person.
As mentioned, the pic collector is typically a pretty pushy and rude soul. They will often be demanding and give little in return. Remember that you really don't need to see too many pictures to size someone up. Have a few you are comfortable with sharing and just stick with those.
Fake people will disappear or dodge any means of vetting them as real.
Certs also aren't always reliable. Some can be faked and there are some from couples who used to swing but one of them has decided to stop for one reason or another. A few of the ones that are fake are the same person with multiple accounts. The inactive ones typically have fairly old certs but that isn't always an indicator.
