Because I am a Digital Marketing Manager I spend a good amount of time online looking at ads. One of the places is on social media in groups. It is being FLOODED with scam ads.
The most reliable way is your common sense. If it sounds to good to be true it most likely is. All of these ads promising $750 from Aldi and others are all scams. The easiest way to tell is to look at the URL or the link where it is going to send you. If it is a promotion for Pepsi it is going to go to the Pepsi website not https://sites.google dot com. That is the main place they are using now. It is a free resource from Google to put up a web page. But it is being used for all these scams.
If you are on a computer the easiest way is to just hover over the link and if you are using Google Chrome it will show the URL link in the lower left of the browser window. If you see that sites.google you can pretty much reset assured if it is promising you something that doesn’t sound right, it’s a scam.