It has come to my attention that Gotham City FX in Lake Mary, Florida is using a product line name from my company, Wolfram Creative LLC, to promote a similar product of theirs on your site. Owner Selman Markovic has just recently been adding "Merc Mask" in his sales description on eBay and other places to confuse consumers, and divert traffic from my company with a similar item. It is blatant misrepresentation.
Just quick note, GCFX was Banned from this site a while back. Consequently any representative of them appearing on this site, i believes constitutes a possible sock-puppet violation of previously banned members.
If all the rules are to be followed, we must assume that your target audience will not at all hear your plea, as GCFX has not been allowed to operate on therpf for some time.
What you kinda are doing, as a side effect is exposing possible sock-puppets or shill accounts.
Regarding what might or might not be considered "fair use":
The determination of "fair use" would normally be determined by a historical observation of the item in question, in essence, if this were a court or otherwise official determining body, the history of the terms "merc mask" will be brought into question.
Can the originator of the phrase "merc mask" prove they have original creative conception of the phrase?
This will be the first question asked.
The next question that will be asked is if "Merc Mask" can be trademarked, it cannot be copywrighted and will not follow copywright rules.
I am going to go out on a limb and say that the presence of the space in the name "Merc Mask" will be identified as a descriptive article, rather than a trade used name.
The trade used name must be identifiable by the parent creator of the name, TMs like "bell atlantic" or "verizon wireless" can occupy that domain, because part of the TM has a wholly used TM name. Verizon would not be able to sue for infringement of the word "wireless" but they can for "verizon" same thing goes for the combination of "bell atlantic" which cannot be construed as a descriptive product phrase, but as the TM and licenced company name.
In OPs case, the separation of merc and mask in this case is a descriptive product name, and would "most" likely be looked at as such and not as a TM type of name.
Now had the name been "mercmask" there is something different entirely.
Also, note that in civil suits, the legitimacy of the product as represented by a TM is irrelevant.