I like pics, with today's date and a phone # on a paper.
No date or phone #, I assume it's fake.
If the phone number posted in the ad is the same as the number written on paper in pictures it does give me some confidence. It's not the end all be all however, check out my review on Brianna Aria -
https://terb.cc/xenforo/threads/brianna-aria-416-567-4083-review.839635/ . Her ad met all the criteria you could want and she even looked believable as the girl in the pics, but her services were borderline a scam; it was one of the worst experiences I've had without being outright robbed. Then there was my recent experience with Paris, her ad basically has all the red flags I would normally run from, but my experience with her was great.
It sucks but there's no quick way to decipher if an ad/SP is going to be legit or a good time. It's pretty lame having to do reverse image searches and terb searches for every picture/number/name in an ad you're interested in but if you do you'll find a LOT if not most of the ads posted are scams and it's worth filtering out. If you're lucky you might find some reviews while doing so but often you're left with no hits, and the choice to take a chance or not.