Oh, I have LOTS of experience with this one.
I've never had a forthright answer from any question I asked of an officer. Not even "How's it going?"
Most often, they know they're breaking the law and aren't stupid enough to admit to it, like they intimidate many others into doing. A.k.a., they don't fall for the same trick that they pull.
I've taken to the "If there is a crime or suspicion of one, I can't help you if you don't let me know. [LEO has mumbly excuses/BS] As I can be of no further use to you, have a nice day." and step away. If they grab you, hey hey, they cannot deny that you are being detained. They cannot say that you resisted or tried to escape, because they never said they were detaining you. You better have a recording, because they WILL lie.
It is best not to stop. Just keep on walking. Once you stop, they don't have to block your path or grab you to forcibly stop you. They love that one, because they don't believe repeatedly blocking you from traveling as you see fit is a seizure, but it is. If they 'just want to talk' with you, tell them they'll have to keep up, you have places to be. If they grab you and force you to stop, bingo.... Some of them will even trip you, and pretend to 'catch' you or 'help you up' as an excuse to grab you or stop you. They taught this in the Academy I attended. They'll add on that you tripped or fell for no reason, and they 'suspect that you are intoxicated,' etc... Watch for it. Some will flat out body check you, then claim you did it to them. Have a recording, video is best.
Even if you don't have anywhere to be, start walking, be in motion when a cop engages you. Walk to nowhere in particular. It doesn't matter. You will either 1) be leaving him/her behind and not have to talk to them (not talking to them at all is the best policy) or 2) they will forcibly detain you and will not be able to argue the point.
You cannot 'flee' or 'evade' an officer by walking calmly, and you would have to be detained, or there be a reason why you should be, for that to apply anyway. If they even try to make that argument, they only bury themselves by needing PC/RAS to support it. Again, they'll lie if they're the filthy sort. Have a recording. Meaning, you cannot evade unless there is grounds for detention/arrest. Detention/arrest requires PC/RAS.
"The Perp evaded me, the Noble Officer, when he tried to walk away!"
"And what was your RAS/PC for the detention?"
"Uhhh..... He had a gun?"
"Sorry, not good enough."
Asking them puts the ball in their court, and they can deflect it by simply refusing to answer. You're asking if it's ok to leave, while not leaving. You're nearly detaining yourself if you ask.
Don't give them the control of the situation they want by asking. If they're going to cross that line, don't let it be a grey area. A decent cop will have no choice but to leave you alone, the filth will grab you and there is no arguing that you were free to go once they do. But, as stated above, the filth will also lie. So you better have a recording, video is best.
Also, if there really is a reason for the stop, such as you match the description of a bank robber from 15 minutes ago; he's gonna grab you no mater what. Most likely you won't be asked... This is probable cause, and justified. You haven't in any way inhibited the officer's ability to do so with any of the above.
They are NOT your friend, and they never want to 'just talk.' They are the paid goons of the most corrupt organized crime syndicate on earth. Some of them really are good people, who have legitimate positive interests. I say this only because there are stories told here of some far off land where cops aren't scum. Remember what they're paid to do; screw up your life to justify the existence of the sham called the criminal justice system. They need to keep roping 'bad guys' to say 'wow, we really need to raise taxes some more, look at all these inmates we have!' If a LEO is talking to you, it's because YOU'RE NEXT, and he's looking for any excuse. Walking away, not stopping, is the best way to assure you won't have a conversation he can distort or misrepresent. If he has a legitimate reason to stop you, rest assured, he will. Don't resist. If he hasn't any reason, he just screwed himself.