I am very talented with accents, but I have had to accept the fact that I am getting older and the ability to imitate an accent is diminishing. I am a native speaker of standard mid-western American English (considered to be accent free in the US). I speak Spanish with several regional accents, due to spending summers as a child in Mexico with relatives, then I lived 12 years in Miami and developed quite a heavy Caribbean accent, and could pass as a Cuban.
I learned quite fluent German at age 20-23 when I was stationed in Germany with the US Army, but I have a slight accent because of what I mention in the next paragraph--rhythm and music.
I live in Israel now, and although I do not use American vowels and consonants in Hebrew, it is the rhythm or music as they say, which gives me away.
At the end of the day, you must admit that it is WHAT you say and that it should be kind and with a good heart. Someone could be the most talented foreign language learner in the world and could learn to speak those languages perfectly without foreign accent, but this person is a horrible and says nasty things! I think we would love and respect the foreign accent spoken by the kind, well-meaning person. It is not the accent, but the thought that counts. Remember that!