Take this for what its worth (not much). When I was teaching remote sit to my pup who was really hot, we started on a rope with no distractions and it went very well, we worked at it for about a month before I added bumpers, I would have her sitting remotely and when I tossed a bumper to ID the pile, she would spin 90* and stare at the bumper, a simple "Hey, Hey!" would put her attention back on me, but she wouldnt turn back correctly. Everytime she did that, I walked right back up to her and nudged her hindquarters back till she was straight, once she was straight, I praised her a little. I did this EVERY time, and never settled. I got very picky with it. After about a week of that she sat straight, but even so, being a hot pup, sometimes the fact that there were bumpers behind her was too much to bear, so I reinforced with a whistle, nick, whistle. After about a week that was the end of crooked sits. I did this twice a day, for 10-20min, 5 days a week. But this is just one guys experience with one dog... I think there are other methods that may be more effective, however, I also believe that the key in straightening this problem out was being persistant and not giving an inch.