Yes. This is how branding works. It's why companies pay for a famous celebrity to represent their brand, instead of a random person, because you associate a higher quality with a famous celebrity.
The major brands have very specific rules on what their ads can appear next to.. they actually write down things like "our ad can't appear next to blood/violence" etc..
Doesn't matter if it's user-generated or not. As long as that image exists next to the brand, the brand is fucked. I mean, what would you think of Chanel if they ever placed their beautiful ad next to a picture of a dead body?