I've had my bachelor leak a couple times but wicked properly it doesn't leak. Every now and then a little bit of juice will appear around the top fill where the cap swings shut, it's more of a slow leak or build up on top of the silicone seal. I leave it laying on its side all night when I go to bed though I close the juice and airflow. No leaks.
There has to be enough wick and the coil has to be just a tad higher than the sides of the build deck. That way when the cotton is extended to either side of the deck in the notches there's enough cotton so it's 'fluffed' a bit taller than the rim of the deck. That's what seals to the o-ring inside the tank. If there isn't enough wick material or it gets pushed down too far into the notches leaving a gap it doesn't seem to seal properly and that's when I've had leaks. Then again I can vape my wick nearly dry with the juice control shut off so apparently mine works properly as far as juice flow shut off.
Mine's the regular bachelor but I think the only difference with the regular and nano are the height of the glass and chimney. Idk, I like it. It's easy to build on if all you need/want is a single coil. I paid $30 or so for mine, $9 is a helluva deal I think.