You have the right thoughts, I think. The details of how you use the term would be determinative of the outcome legally, I think. Sure you have the right to say your dog collars are "manly" if that will not make people confused as to source between your products and the registrants collars. There are multiple factors that are used by courts to decide these issues. For the one used by Federal courts and the patent office, Google "DuPont factors". You should get an attorney to assist you in this analysis, and you know that or you would not be asking us here on Avvo. Hire one so you can go over ALL the factors in confidence and not potentially tip your hand to the registrant here with too much detail.
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.
Trademarks are designed to identify the sources of products and services. Infringement of a trademark occurs when someone uses it in a manner that creates a likelihood of consumer confusion as to the source of goods and services. Further, trademark law is limited by the First Amendment, which allows fair use of a trademark if no consumer confusion is created and/or so-called nominative fair use which allows a trademark to be used to describe the source of goods and services in an article that reviews or criticizes such goods an services. Your question demonstrates that you have a grasp of some of the nuances involved here, but you have not provided sufficient information to permit me to analyze whether the use on your web-site of "manly dog" would constitute a violation of trademark law. I don't know, for example, whether the products which you are selling (presumably dog collars), compete with products sold under the Manly Dog label. I also don't know the precise context in which you used the term. If you simply described a dog collar as "manly", that would probably be protected as fair use. But if you used the term "Manly Dog" in a manner that might be understood by some consumers as providing a brand name for a product, then you could be creating consumer confusion.
You are on the wrong track in your thinking in one important way. You presume that most people searching for a manly dog collar are most likely not searching for a particular brand. First, I don't believe that assumption is correct---I doubt if there are a lot of people searching for generic, unbranded manly dog collars. But even if you are correct, this is besides the point. At least some people will search for the brand "Manly Dog", and the problem here is that your use of the phrase "manly dog" in your web-site may cause your web-site to show up when persons search for "Manly Dog". In so doing, you may be converting traffic to your web-site that was intended for the Manly Dog web-site, and perhaps taking away sales and business from the brand. If Manly Dog's lawyers can show that you are diverting traffic to your web-site, that might be sufficient to show that you are creating likely consumer confusion.
Further, why would you want to fight this issue with the owners of the "Manly Dog" trademark? After all, the brand owner does appear to have a valid "Manly Dog" trademark covering dog collars. There is at least the potential that some consumers could be confused by your use of the phrase "manly" in this context. And you can make the same point using other phrases---"dog collar for men"; "masculine dog collar" etc. Why would you want to run the risk of an expensive trademark suit when alternatives are available to you that get you the same place?
If you want to continue to use the term "manly" in this context, then you would be well-advised to retain legal counsel to analyze the specific facts and circumstances of your use compared to the "Manly Dog" brand. It is by no means clear that you can avoid a costly law-suit in this situation, but if you want to fight the issue, you may be able to avoid a finding of willful infringement (and punitive damages) if you obtain written legal advice from legal counsel that supports your right to continue to use the term "manly" in the context of your web-site. Without a written opinion from legal counsel supporting your position, you are exposed to potential punitive damages for willful infringement (especially because you made the mistake of many admissions against your interest on this publicly available web-site).
My colleagues have expertly analyzed and advise you about the legal consequences. I just want to add that many times the answer is not legal but business and financial. I mean what is the cost of changing the word "Manly" for an alternative synonym that may convey the same virility perception and what is the cost to deal with the legal aspects of stand your ground.
Sometimes is not enough to be right to have to have the financial means to defend your stand.
Only you, in strict consultation with your attorney, can determine what is the best course of action.
USPTO Registered Patent Attorney, Master of Intellectual Property law, MBA I am neither your attorney, nor my answers or comments in AVVO.com create an attorney-client relationship with you. You may accept or disregard my free advice in AVVO.com at your own risk. I am a Patent Attorney, admitted to the USPTO and to the Florida Bar.
Q: "What is considered proof of confusion in a trademark?"
R: (1) Sworn testimony from impartial consumers of the allegedly infringed product that they were confused about who actually made the allegedly infringing product,
(2) Sworn testimony from impartial consumers of the allegedly infringed product that, upon viewing the allegedly infringing product, they believed that it was either sponsored or endorsed by or somehow associated with the company that makes the allegedly infringed product,
(3) Sworn testimony from suppliers or other relevant marketplace participants as to the type of confusion described in (1) and (2),
(4) Survey results from impartial consumers who, after viewing both the allegedly infringed and infringing products in the way both are presented in the marketplace, respond to questions as to their reactions when viewing those products,
(5) A negative change in the direction of sales by volume of the alleged infringed product after the allegedly infringing product was released to the marketplace,
(6) Any other confusion evidence specific to the case.
The above is general information ONLY and is not legal advice, does not form an attorney-client relationship, and should NOT be relied upon to take or refrain from taking any action. I am not your attorney. You should seek the advice of competent counsel before taking any action related to your inquiry.