The first photo right shows the Porte Saint-Denis. This 25m high triumphal arch was inspired by the Arch of Titus in Rome and lies at the top of Rue Saint-Denis. It was designed by architect François Blondel and sculptor Michel Anguier and was built in 1672.
The next photo shows a group of adult shops. I cannot say they are all rip-off joints but when they use the word "club" and you see pretty girls hanging around (as in this photo) they should be avoided. Paris is like london and the underground nature of the adult industry means scams are rife. This is not Amsterdam
The first photo on the second row is a common sight in Paris. It's pretty obvious that many of these people are in genuine need but remember a lot of beggars are no better than thieves. They will fain disability and tell lies about their hardship.
The last photo shows Mc Brides Irish Pub at 54 Rue Saint-Denis. This is a good example of the bars on this street. As you go further south there are more and more nice restaurants, fashion shops and bars and the adult element slowly dissapears.