A large portion (if not a majority?) of those 140 million travelers go through organized tour groups, where they jump from attraction to attraction, staying half an hour or so to take pictures before rushing back to the bus to head to the next stop.
This French photographer was allowed to join such a group and it's fascinating:
http://www.slate.fr/grand-format/touristes-chinois-europe-je...
Choice quotes from the photographer (translated):
"Costs are cut on everything. For 10 days, we ate Chinese food for lunch and dinner. Before I started this project, I thought that tourists always ate Chinese food because they weren't curious. But cheap backroom cafeterias are imposed on them, where the meal (often inedible) costs 5 euros per person. We only took 10 minutes to eat, and I'd always be the last to finish. After Paris, we were supposed to sleep in the "French village" of Dijon [original is in quote because Dijon is a large city]. But the hotel was situated along the highway, at Sauvigny-sous-Bois [about an hour away from Dijon]. That night, with Lan, we decided to take two people to Relais Fleuri, a nice restaurant next to the hotel, without the guide, so they could discover French gastronomy. When we got back, the guide was really upset. The next day, I got an email from the agency saying that if it happened again, I'd be kicked out from the group."
"The majority of guides are not there to teach. When Chinese tourists go back home, they haven't learned much; in fact, stereotypes tend to be reinforced [...] a few of them complained about the [Chinese meals], and that they wouldn't visit markets, for instance, but those criticisms were very limited. It's a shame, because the only contact they have with French people is at the register, when they buy something."
"I was shocked by how resigned people were. You're not supposed to disagree with anything. The guide was considered like a boss whose orders had to be followed, and who should never be contradicted. Ours was 34 years old, and went into tourism for money. But he didn't know anything about Europe, and spent the whole time telling cliché anecdotes about cities. He even got monument names wrong! His only goal was to sell additional options, such as gondola rides, to get a bonus."