Here's my take. Mind you, I've been a detentions deputy for 5.5 years and am now not quite halfway through FTO for Patrol.
0415 one morning, white male wearing a backpack walking down major street in my sector, semi-industrial area. My FTO and I call out citizen contact and go talk to him.
"Hey guy, just wanted to talk to you for a minute. There's been burglaries around here and we were curious if you've seen any wierd stuff going on." BS, but it's a reason to talk to him. Turns out he's walking to work at UPS, even knows the exact mileage to and from work. He lost his license so he walks. Legit guy, willingly gives me his ID and even tells me he got a letter yesterday saying he missed a court date.
Sure enough, I run him and he goes to jail. Good stop? Absolutely. Until I found out he was wanted, he was free to tell us to pound sand and walk away. He didn't even have to give us his ID because we had no RS to stop him. Turns out he had work clothes and water bottles only in his backpack. Nothing illegal or suspicious on him.
It's all in perspective. You can stop anyone and talk to them at any time in any place, as long as you understand they don't have to tell you jack, unless you can articulate good RS to question them.
Edit to clarify search incident to arrest