Hi Steve,
I'm still delving into this area, and learning about how it works...
People who know what they're doing avoid "live" trademarks like it's toxic. The reason why is because the trademark owner can usually legally take your domain name away, and not have to pay you a cent... So financially, it makes sense to avoid any live trademarks.
But domain names people do register for resale can be divided into multiple categories...
Exact match domains are a big category. These are domain names that match exactly popular search terms people might type into Google.
As an example, people do type in "poison ivy rash" into Google. So,
PoisonIvyRash.com would be an exact match domain name, which could be of value to someone selling products to help deal with poison ivy rash. (There is no trademark issue here... In this case, poisonivyrash.com is already being used.)
Another category of domain names are search engine optimization (SEO) domain names. These are expired domain names which have a lot of existing good links going to the domain name. These could have resale value because of the existing traffic. (But you have to avoid those with a lot of "toxic" links going in - as that will hurt the Google ranking...) The final buyer of the domain name would probably create a new website at that site which is designed to benefit from the existing incoming links...
A third category are brandable domain names. There are several resale markets focusing on these. Three such places are
Squadhelp.com,
Brandbucket.com, and
Brandpa.com.
Domain name sellers can list their domain name in one of these places. The website (Squadhelp etc.) will create a logo, which sells along with the domain name.
As an example, I typed the word "poison" into Brandbucket, and some of the possible "brandable" domains which I could buy which came back were "Poixen.com" ($2,875), "VenomVentures.com" ($3,595), and "Vynom.com" ($1,995)...
So there you have it!
I'm still a "newbie" at this, though...
Best wishes,
Dien