Asking if you can leave is not acting like an ass!
What the AC said is the best thing. Offer to be helpful, and if they don't want immediate help ask to leave. Repeat until freedom.
They do want your help, because "anything you say can be used against you", tell them that you will not speak to them without legal representation, and that you would require (the USA version of) legal aid. That calls their bluff: they have to either arrest you for nothing (opening them up to a poor pay review, civil legal action, whatever), or you can't help them. And if they were going to arrest you from the off, they would have done so already.
I guess it depends on how you ask. They can detain you for questioning based only on reasonable suspicion, which they likely would have if they stop you. As for the Miranda decision, that ONLY applies if you are under arrest. Otherwise they can ask you anything without an atty, and have no obligation to provide you with one. There is no bluff because, as I said, they can detain you, question you, determine your involvement or lack thereof. And contrary to TV shoes, not all arrests are made within the officers first 2 minutes on the scene. And I am not sure from whence you hail, but officers here are not subject to poor pay reviews and civil action unless you can show non or malfeasance. Simply arresting someone and then later having to nolle prosequi the charges does not mean they acted in bad faith. Oh sure, you can try to sue, but you likely will get thrown out of court unless you can prove bad faith or malfeasance in some way.
I must say, this street level "How to Deal With Police 101" is rather entertaining. Makes me wonder how many people here have meth labs or grow light arrays in their basements, or how many are habitual offenders out on the highway.
I will grant that there are bad cops, just as there are bad teachers, doctors, nurses, bus drivers, librarians, etc. Get a big enough group and you will find bad apples. But, I have had a few tickets and was even arrested twice on warrants obtain by my ex (later dismissed summarily) and with the exception of one State Trooper giving me a RADAR ticket, EVERY time I had interaction with Police, I was dealt with professionally and courteously. Dealing with police is kinda like posting on
Chemist who falls in acid is absorbed in work.