Ditto.
My home computer has left-handed mouse, left-handed button configuration.
My work computer has right-handed mouse, right-handed button configuration.
I have absolutely no problem switching between the two, and honestly don’t even notice it… but those folks that put the mouse on the left and **don’t **switch the buttons mess me right up. I can’t get used to that.
Right handed, but like lot’s of people above, I mouse with my left (with buttons swapped), to avoid soreness in my right hand. For a long time, I only had my main work computer set up this way, and moused righty on other computers. Recently, I’ve been changing all my profiles to mouse with my left hand.
No, but when I used to doodle, I noticed I would doodle differently with my left hand. I’d make more geometric doodles right handed, but tended to draw people or things like flowers left handed. Part of that might have been I couldn’t draw straight lines very well left-handed.
ETA: It might depend on what you’re using the mouse to do. I’m usually just navigating, or programming, or writing. The hand I mouse with might not matter much. If I was drawing pictures, then it might have more of an effect.
Another lefty who uses the mouse right handed. It started because the first mice were all right handed, and then I figured out that it let me use a pen without having to put it down every time I want to move the mouse. I’ve never figured out why more righthanded people don’t use the mouse left handed.
As for the OP, I can use a left handed mouse, but not nearly as well as a right handed.
I usually move the mouse to the left at work, too, and when other righties move it back on me, it doesn’t bother me. I guess that’s the difference between having one thing different and having lots of things different, after a lifetime of being different. 
I can use my mouse with my left hand, even precisely. I often do this when I’m helping someone with a computer problem and I happen to be standing to their right.
I do some things left-handed and others right-handed. I use a mouse left-handed at work, and right-handed at home (because it pisses my wife off if she uses the computer and the mouse is set up left-handed). I am equally comfortable either way.
This brings up ergonomic design. My laptop has all the USB ports on the left side, so I have keep the mouse an extra couple of inches away from where I’d use it more naturally.
Also, when using the mouse right-handed I often use Windows CTRL-C and CTRL-V commands with my left hand while leaving my right hand on the mouse, but have to take my hand off the mouse when using it left-handed. Same for using CTRL-S to save a file, ALT-F-S to save a file with a new name. I’m wondering if they designed those commands on purpose.
I write left-handed and cannot use a stylus or other fine tools effectively in my right hand. I throw a Frisbee with my left hand, but throw anything else right-handed. I use cooking utensils left handed, but knives right-handed. I bowl right-handed. I wear my watch on my right hand because it gets in the way when I write. But then I have to take it off to set the time.
It just goes on from there…
I can use the mouse with my left hand (I’m normally right-handed) reasonably well, but I don’t do it particularly often, as the need doesn’t appear that much.
Wow - my son is exactly the same on all of these (well, except perhaps cooking utensils as I don’t believe he has ever used any…). I thought he must be unique to throw a frisbee lefty and everything else righty.
Lots of people agree with you. It’s really no big deal, even for a hardcore Righty, if that is how you learned.
My Ambi hubby secretly thinks I encountered more, meaner Nuns than he did in school.
I think I was (and am) simply too lazy to rearrange my desk, which is reinforced by the fact that I went to Public school 
right handed person here, and I am a total klutz with my left hand.
However, I can only use a mouse with my left hand. It just seemed natural when the numeral keypad is on the right side of the keyboard.
Strangely, on a touch pad, I am 90% right handed. but I click the left button with my left hand index finger.
That’d be me. I can use either hand equally well, but never switch the buttons. I started using my dad’s computer (he’s lefty, I’m not), and I’m not really sure when I started using a rightie. I just put the mouse wherever it makes sense on the desk. For a long time my work computer was left-mouse and my home was right-mouse.
The work thing was fun, especially when someone needed to “show me” something. They’d look at the mouse with a blank stare for half a second and then look at me like “What is this strange device and how do you expect me to operate it”?
Wow, how strange. I write left handed, but have never used anything other than my right hand for the mouse. Never even gave it a second thought.
I’m right-handed but I mouse with my left hand because I like to jot down notes while I’m surfing the web. The button configuration doesn’t matter to me. If I’m on someone else’s computer I’ll switch the mouse around; if for some reason I can’t move it where I want to, I can use the mouse with my right hand, but it feels awkward.
Dominant hand at work; subordinate hand at home.
Something in the back of my head states I should equally distribute Carpal-Tunnel syndrome.
I can do very little fine motor-wise with my left. I’m a right-hand mouse user all the way.
I didn’t either until I started to see threads here about it. I’ve never bothered setting a mouse for left hand use. Right handed works just fine.
It was easier to learn how to masturbate with my off hand.
I can, but I have an ergonomic gaming mouse, so it’s not very comfortable, and the thumb buttons are useless. So, yeah, but I don’t like to.