what types of internships are scams?

<p>I was browsing through the career employment search engine on my university's website, and I found one company who was looking for a marketing representative to help promote their sales. So I sent in my resume, and they contacted me and told me that I get 20 bucks for every customer who buys from them. My job is supposed to advertise their company on campus (handing out flyers, talking to people) and online. Is this a scam? Will they really pay me if people from my university buys from them? I am also the only marketing representative for this company in my university, so there shouldn't be any confusion as to who the money should go to.</p>

<p>My question is that there are a lot of internships where students participate in promotional activities and other stuff, and I found many internships through my university's website, so that's why I'm more prone to trust them, but are they just a waste of my time and merely a scam? or are they legit? how do you decide whether an internship is actually authentic and worth investing time in?</p>