Is it Always Easy to Treat Others as You Wish to be Treated?
Not everyone is easy to get along with. There are people who are meant to be left alone. Rude people, evil people, people who can't ever find anything positive to say - they are all not worth mixing with if you can help it. When you are a kind person, there are those out there who may try to exploit you for one reason or another. Without making yourself to be the fool, it is wise to approach people with cautious optimism, being friendly to all in greeting, and leave it at that. Whatever happens beyond that point, you know that you did your part in being nice.
Everyone is required to live peaceably with others, so long as it's reasonable. With that in mind, people often have "gut-feelings" about others upon that first meeting. Sometimes it can be hard to find a topic of conversation with someone whom you may not feel comfortable around. If that happens to you, you should not feel guilty about excusing yourself and walking away. Better to do that than to make an idiot out of yourself when attempting to defend yourself against a person who has bad intentions.
While it is true that you can catch more flies with honey than with vinegar, not everyone has a patient temperament. Not everyone can make friends easily, be an interesting conversationalist, or have witty jokes at the ready. Being polite, however, is an essential trait to have for effective communication, regardless of whether you expect someone to respond in kind or not. You are not to assume that a person will be a selfless as you are, just as that person can't know if your niceness is genuine without really knowing you. Instead, you have to always smile and make eye contact when interacting with others, not going out of your way to be rude or mean to strangers or acquaintances. When you can do that and know when to walk away, you can become better able to extend feelings of good-will to everyone you meet, without worrying about the risk of rejection or embarrassment, because you simply don't care of what others think of you. Rather, it's what you think of yourself and how you treat others that matters most.