Just received a text for a job paying $500 a week to post online ads. The sender texted it was in response to my resume post and gave the company name after I asked. Not so sure I should trust the sender as this feels like an unconventional way to present a job opportunity.

Well considering that posting those ads would probably be illegal to start with, well yeah, I guess you should be suspect of that person.  Especially at that high of a rate of pay for a menial task.  Don't worry, they will ask for money somewhere along the line, or they will send you a check that is way over the $500 for the first week and tell you to send the difference somewhere by untraceable means.  Then the check bounces and you are out the money, the bank fees, and depending on how big the check is you may also face criminal charges as well.