Trek rebrands a lot of accessories with their logo. Some of thse items are better than others. I had one of their under the seat wedge tool bags that I was quite happy with until I realized the cordura nylon was wearing holes in the thighs of my bike shorts. On the other hand, a Trek branded taillight fell apart when I was trying to install it with my bare hands... and I'm no amazon. Since then I've decided to stick with third party accessories from companies like Planet Bike or Cateye and avoid most rebranded items from Specialized and Trek.
One item I do like from Specialized are their Armadillo tires.. but I don't think there's anything to prevent you from putting them on a Trek, Bianchi, Raleigh, Jamis, or whatever else you might have.