I was doing a music video last week and the other actresses and me got on the subject of postings that are obviously scams. Interestingly enough we all had the same idea.

Clear sign that it is a scam:

The entire posting is in caps

It is a one line ad such as : Hot latina models needed now. $$$$$

It has a ridiculous amount of money being offered ($1500 a day). If it's too good to be true it probably is. If they could afford to pay that much they wouldn't be posting independently and might just go through an agency.

Oh and my favorite: Seeking Open Minded/Flexible models/actresses. I love how open minded and flexible has now became interchangable for "willing to get naked for a shoot". 

It is also best to respond to people that have a legitimate email address and a link to their work in their posting, which is unfortunately 1% of people who post online but just use your best judgement and do your research.