You've probably heard already, but people are using Tinder.

In fact, 13 million people are using Tinder overall with 10 million people opening the mobile app on a daily basis, research has found. And the majority of users - more than 50 percent - have come from the 18- to 24-year-old milennial demographic.

But with this online dating app, there comes a darker side. Not everyone online is who they say they are, and there are surely some profiles to watch out for.

Here's a list of six users to keep your eye on when you're swiping through.

The groupie

Group shots all around. This user has photos, but they're mostly of group shots taken with their friends on the sandy shores of the Pacific Ocean or at a late night bonfire. Be careful with this user - you may not know who you're going to be talking to, and they may not be very honest about themselves.

This users also committed one of the seven deadly sins of Tinder, if that tells you anything.

The no-face

So you're swiping through, having a good time and you fall upon a generic profile face without any real photos behind it. While this person could be good for you to show you don't care about looks, not placing any photo shows there's a sense of mistrust.

The odd photo

Seen a guy with a tiger? Or how about just a cupcake? What about a house or a tree? These type of photos are common on Tinder and don't really put you into direct conversation with someone. Though some have found the idea of dating a cupcake appealing.

The two-picture chump

There's definitely worse out there. But, come on, just two pictures? You can definitely do a lot better than that. Three should be the gold standard.

The one with no info

They got the photos, but they don't have any info. You can look through the photos, but won't learn anything about their personality. Not exactly a great option for dating.

The scammer

Yes, scammers exist on this new social media app. In fact, Tinder has been known quite recently for having scammers on their app. These people pretend to be regular users but end up trying to get more information.