Any source would be good.
There are a fair amount ive seen in Paris.
There's the classic pickpocket, most work in pairs. One makes a distraction while their partner empties the patron's wallets/purses/bags of money. Some go as far to actually chunder on a busy train or chuck a fake baby in your arms.
There's the 'Gold ring scam' Where a worthless metal ring plated in cheapy gold or brass is dropped behind the person. This is where the scammer will pick it up and rush over to the victim. They will insist that it was the persons, and try to force it onto your finger/into pocket. Next comes a small sob story and asking for some money. If you give them a paltry amount, they ask for more because they found a nice ring for you, thats 'gold'. So they end up with some dosh while you have a threaded bit with green plating on worth about 50p.
The 'petition' scam is where they will rush up to you and really, I mean REALLY get in your face, asking you to sign this petition. This can go either way, where the friends will mine your pockets, or they ask for a donation to the 'cause'.
Another one is where these gentlemen will beeline to you and will commonly have the audacity to grab and restrain you to attach a 'friendship bracelet' to your arm, then demand an extortionate price (say 20-30 euro). They will go about harassing you or threatening to cough up. I find this very intrusive especially to women that they also prey on normally.
I will also indulge you on one that I experienced a few years back, where a well suited man will 'help' you buy your ticket, you give him the money and he gets a cheaper ticket for you.
What they don't tell you that it's not what you wanted, normally one way to the wrong stops.