Some folks like to characterize other folks who disagree with them as "unAmerican". What the hell does that even mean? 7Up used to be "the UnCola", and that was taken to mean "not a cola". If one is said to be ungentlemanlike or unladylike, everybody knows what that means. But unAmerican?
Being an American involves nothing other than a geographic accident; therefore, the only way you could be unAmerican would be to hail from somewhere other than the Americas, or since we have coopted the word, the US. There is no way to be American other than to be in America. You can hold all kinds of beliefs and opinions and engage in a variety of practices, all of which would be American because you are in America.
There are no distinct and nearly universally held ideas that comprise an American ethos. So, when someone says of another person or idea "that's unAmerican" this translates to "that's quack woof kerblah"! It's nonsense.
Another nonsensical statement is to attribute something to the "Blame America First" contingent. This label is applied to anyone who criticizes US government policy abroad, and there is already a perfectly cromulent expression "critics of US policy abroad" that is much more accurate and descriptive. The use of Blame America First as a label is an ad hominem attack that says more about the user than about those he or she attacks.
Another idiotic exercise involves exchanges about whether one's patriotism has been questioned or whether it is subject to question. A patriot is one who loves one's country, but some would add an additional requirement that a patriot also be an unquestioning supporter of the government. When someone talks about patriotism, we don't necessarily know what the speaker means, so we should ask for clarification and definitions or just ignore this as nonsense. Patriotism has more often been a cover for douchebaggery than a sign of anything good.