You're talking a lot about punishments, but how are you rewarding?
First, I would draw the line at having them do anything for punishment that you want them to do all the time anyway. Your kids shouldn't see having to do the laundry or clean their room as punishment, those are activities they should be doing every day. Because of that, it's about as useful punishment as being told they have to brush their teeth for punishment.
A lot of the time, the apathy they are showing for the punishments is from the punishment being overused. It loses its sting.
I would suggest finding something to motivate them in a positive way. Give them something to anticipate and work for, and the "punishment" is that they don't get that thing. It can be anything, based on what they like. My kids are big into video games, so as a way to cut back on gametime (they wanted to play every day) and to motivate them during the week, we only have games available for the weekends. They know this, and they know that if they get in a certain amount of trouble (be realistic in your expectations -- don't automatically say they can't do it because on Monday one of them smarts off), they don't get to play that weekend, and will just have to try harder the next week. They're six and four, and this is working out relatively well. The realization that they lost their last chance to play games for another week is more effective than most anything else.
It's important to mention here that it's not ever put out there as a bribe. We're very careful not to say "IF you behave". Saying that kind of opens them up to be able to decide that good behavior is optional.
I would say, instead of sitting your three-year-old down and trying to talk about "what he did wrong", sit him down and talk to him about what he should be doing right. Try to encourage him to be empathetic, realizing that his actions can help or hurt others, and make his discipline go along those lines. For example, if he hits his sister, he has to give his sister something (typically, fights over video games in our house end with the one who was in the wrong -- if it was just ONE of them -- having to put his controller away, and knowing that the other is still in there playing Mario).
With the time outs, they look at you like "you've got to be kidding, right?" because they know you aren't going to stick to your guns. For a while, one of my kids was like that, but he changed his tune after I camped out right by his time out corner and everytime he talked, I told him he was not allowed to talk, and every time he tried to turn around, I told him to stick his nose back in the corner. It only took a few times of showing him that I was as adamant about him doing the time out as he was about not doing it and that I most certainly WAS serious, before he started realizing that it was not optional. Don't lose your cool, just tell him to get in time out. When he looks at you like he thinks you're kidding, force him to do it. Doing that enough times will show him that you mean it.
Of course, I don't know, but it just seems to me that you are so focused on the negative, punishing instead of motivating, that I can understand why your kids aren't responding to it. Add to that the fact that you aren't all that consistant (they dont' know if what they're doing is a spanking offense, a time out offense, a discussion offense or a cleaning offense), and I can see where you're having problems.
For their sake, I would strongly suggest that you try very hard to try to reward or praise them as often as you punish them. It's disturbing to hear a parent who describes their children in almost entirely negative terms.