Sometimes, it's as simple as reminding them who is the parent...and it took me a while to grasp that. I try not to make it about the task, but about the behavior.
If my son acted up in public, he was removed immediately - no negotiation. He got one simple warning: Stop it. You are being rude and disrespectful. Then, he was out and I made sure whatever came next was even more boring than whatever we'd just been doing. As far as tasks, I made sure that he knew it wasn't about the act of putting the clothes in the hamper (I had that one too.. sorry.. I feel the pain) It was about being respectful of me, doing his part, tried to instill a bigger picture, if you will. Sounds too much for a 4-5 year old - but I found if I only took away privilges for "not putting the clothes in the hamper" no big deal. If I said he was being reprimanded for being incosiderate, it sunk in, and carried over.
And...I wasn't afraid to reprimand. He's never been spanked, but I have terrified him with Scary Mom as he called it. Not screaming, but a signficantly increased volume and never breaking eye contact - I save it, so it makes impact - When he went in the street, which he never did again -I said I was angry and scared becasue he could have been hurt and it was my job to protect him, but I couldn't if he didn't listen. Another was a spectacular display of brattyness in a shoe store. I carriedd him out without a word, leaving everything. put him in the car and told him in no uncertain terms and volume exactly why i was angry. I used words like brat, rude, obnoxious, horrible. "I love you, but I didn't like how you behaved." and again "It's my job as a mom to make sure that you know how to behave. I cannot let you grow up thinking that that behavior is acceptable" I've been reprimanded once or twice for my approach - but I now have a son who can observe others and say to me "That was really bad manners mom. They shoudln't be like that to other people." and he puts his clothes in the hamper. :)
The golden rule helps.."How would you like it if I didn't help you with something? or if I spoke to you that way?"
The key is, for me, he needs to know what the core behavior is that is being corrected - not so much about what NOT to do, but instilling the standards of behavior that will guide him as to what he SHOULD do in all situations. It has worked for us. He's well mannered, sweet, kind, affectionate, generous, and helpful.
Don't know if that helps or not..just had a cup of coffee so i'm a little wired. :) So somewhere in that...talking doesn't always work. The bigger picture is important. and always remember...YOU are the parent. (dang that was hard for me to learn.)
Best of luck!