My understanding is that trademarks afford protection when used as an adjective to represent goods or services, but they do not afford protection for generic usage of a trademarked term and only limited protection (whatever that means) for descriptive use.
One assertion is that if a company trademarked the term "influence" (or similarly spelled terms like Nfluence or influenSe), then such trademark registrations do not remove the word influence from general use. Hence, is it correct that anyone could still use the term "Influence Score" to refer to a measurement of influence even if the trademark owner uses InfluenSe® Score or Nfluence® Score? How concerned should our startup be that our use of the term "influence score" would result in a cease and desist letter that will require costly litigation to defend (or would a the courts quickly squash a C&D) regarding generic or descriptive use?
As a real-world case-in-point, the definition of "clout" includes "influence", and KLOUT is a registered trademark of Klout.com. Hence, a clout score (or a klout score) is similar to, or a type of, an influence score. If our startup has offerings that include the use of a clout score (which is a measure of one's influence or clout), how easy would it be to get any potential legal action squashed due to our generic usage (or should we budget large amounts of money for a legal defense)? Should we be concerned that use of the term "clout score" would invite a cease & desist or legal action?
Also, would your answer be any difference if the five-year contestability period has expired?
Your question about whether something is trademark infringement is first in the eyes of the trademark holder, and then in the eyes of the USPTO and/or court. But this question is not as much about trademark infringement as it is about (a) whether the trademark holder will take action, such as via a Cease & Desist (C&D) and then (b) the likelihood they will prevail in litigation, if any.
If Klout, Inc follows the lead and success of EMI with the "entrepreneur" trademark (which goes back to the 1970s), there could be many C&Ds or even expensive litigation on the horizon. In Klout, Inc's brief six-year life, they have taken action much quicker than the litigiously-prolific EMI. Klout, Inc already issued at least one C&D (to PinClout.com see here ), and they prevailed with just a C&D letter.
There are many other busineses and websites using the term "clout", so this may be an interesting situation to follow.
It's very hard to know in advance. I would recommend steering clear of anything which anybody might ever find confusing. For example if you started telling me about clout scores, I would think that you were misspelling klout scores. If you told me about it over the phone, I would be certain you WERE talking about Klout scores. The possibility of confusion in the consumers' mind is exactly the thing that trademark law is meant to prevent so why not give them a wide berth and choose terminology and trademarks that are miles away from the incumbents?