Others might get extremely uncomfortable with your compliment, and as they do not know how to accept it, they will come up with a sassy response. Depending on your tone, some girls might take it as an insult, thinking you are trying to mock them. If you mix this attitude up with the American way for example (the kingdom of empty compliments and fake niceties), be prepared for chaos. I am generalising, but most of the people I know have no idea how to react to a compliment because they are not used to getting one (not a genuine one at least).
Her boss said: “Don’t worry, I’ll tell you if you do something wrong”. She was starting to get really nervous, so she asked her boss if she was doing everything OK. To give you an example, my friend has worked at her new job for several months, and no one told her anything about her performance. We are not used to praising others or hearing others praise us. I believe this is because we are not a “complimenting nation,” which is a shame. You should be prepared that a Hungarian will not take your flirty compliment as smoothly as you would expect.