Photographic styles have certainly changed. In old time photos, people seldom were seen smiling. None of the photos in the above posts evidence that Huguette was ever very happy. She was probably emotionally abused from the outset.
In 95% of photos, people looked like they were walking up the stairs to the Guillotine. What was up with that? Bad attitudes or bad teeth?

Clark made his greatest fortune in the Southwest. His United Verde copper mine, in Jerome, Ariz., yielded a profit of $400,000 a month, or in today's dollars, $10 million a month. The trading post of Las Vegas was a stop on his rail line. Here he speaks to a crowd in Las Vegas from his Pullman car in 1905. Las Vegas today is in Clark County, named for him.
That's because they were instructed to do so by the photographers. The exposures were several seconds long and the subjects had to hold perfectly still the whole time. It is essentially impossible to hold a natural-appearing smile for that long.