As an American, how much would I be harrassed/shunned/treated differently were I to visit and/or immigrate there?

I ask this entirely in good faith, because I am very concerned about any possible future leaving the country either for vacation, work trip or immigration. I know our reputation is shit. Assume that I (or any other hypothetical American) are “good tourists” - not loud/obnoxious, not being assholes, trying to integrate as best possible, being courteous, speaking the language (as best possible) etc. same applies for immigration. Would you treat them differently if you found out their political affiliation? If they pretend not to be American? Or any other possible modifiers.