According to this data from comScore, 18-34’s pay more attention to advertising messages on UGC sites than they do traditional websites when it comes to products in “high fun” categories, i.e. “Apparel, Music/ Movies/ Entertainment, Food & Beverage, and Consumer Electronics”. Less so for stuff like banking and medical info (known as “high trust” categories). Here’s the requisite chart, lifted from the comScore blog:

Frankly, I also suspect that part of the reason there’s a difference between trust factors based on product category is the nature of the product category, rather than just the delivery agent for the messaging. 18-34’s spend way more time and money thinking about and spending money on “high fun” products than they do “high trust”, so their knowledge, comfort and interest level is different. If 35-55’s were as well-versed in new media, I bet their graph would trend in the exact opposite direction.