Im not an attorney, nor do I play one on TV, but I do use trademarks and work with our attorneys to register them. Also, the owner of my company is a recovering attorney and I asked him for verification. Ive never heard of a local mark. When I asked him about the local (state only) trademark issue, he chuckled. Trademarks are not generally local. While it might be possible that a state would offer such a service, why would anybody serious about protecting a trademark register their mark in a state only? Thats just plain silly. There are some restrictions in doing business state-to-state based on company-name, but thats a different story.
General guidance for trademark use:
R with a circle around it indicates a registered trademark. It involves performing an initial search for items with the same name, filling out paperwork, proving use (showing it on packaging, shipping it out of state, etc.) and paying an attorney a bunch of money to make sure nobody else is trying to do the same thing. Until a trademark is registered, you can put TM after the word to indicate that it is used by you (no attorney assistance required), but it isnt registered yet. You can use the TM indefinitely, but if youre serious about a trademark and think you might need to enforce it, register it.
Do not use the mark as a noun. Trademarks must be adjectives or they lose their trademark status. Sometimes the exact noun will vary (well sometimes say Wallwear wall and corner guards, sometimes, Wallwear integrated wall protection systems) but it cant be used as just plain old Wallwear. Companies make this mistake all the time and it dilutes the ability to enforce the mark if they ever really needed to.
To use a trademark, Insert the R or TM after the first use of the mark on a page. After that, just use the word alone, but continue to capitalize it and spell it exactly the same. Do not, for example, use the word wallwear, only Wallwear when describing our wall protection products.
I try to protect our marks by making sure that they are used correctly (as per guidelines above) in our own literature and that of our representatives. Regarding your fellow in Iowa why is he bothering you if youre specifying his products? Seems to me hed have more luck selling his products if his trademark were being used, correctly or incorrectly. I correct people informally (verbally) when they use our trade names to describe somebody elses product category, but Im certainly not going to make a big case out of it. After all, if somebody were to google that name, theyd get our website.
P.S. Dont tell google I used their trademark as a verb. That really irritates them.