yet another seized bb

Just stripping my Marin MTB and the bb is showing signs of age. Can't get it our but oddly the plastic cup is drive side and not screwed fully home, while the non drive side has the metal cup and is as tight as can be.....I'm still presuming that its anticlockwise to unscrew the non drive side as the plastic cup is well bolloxed now. Long bar and heat?

If you can get one cup out could you belt the spindle out leaving just the other cup in place? Then maybe employ sheldons bolt, washers and nut method? Failing that maybe if you get the spindle out could you dremmel the remaining cup?
Have you tried soaking it plusgas ?

Half the plastic cup is out, I'll try the hammer method and get some plus gas too. But I didn't think the cups could be swapped from each dide

They can't.

But if someone flipped the bike upside down, got confused which side of the bike was which and took to it with a bb tap...*

I have never done this. Honest. Maybe.

Have you tried a long lever and the trick of bolting the remover tool onto the end of spindle (on the cupside you want to remove ) which stops it slipping. Wrap the BB cup and frame in a little bag or cling film to create a little pocket and fill it wd40 or plus gas so that the cup is submerged then let it soak.

Bolted the removal tool to the bb, long bar, no joy. Now for a good soaking. Failing that I'll bring the side of the cup off which might relieve it a bit to try hammer and done sort if chisel. Will not be beaten

Do you have a vice? Clamp BB tool to spindle, then clamp the spanner flats of the tool into a vice and use the frame as leverage. Start by rocking then put some weight behind you - it works most of the time.

haven't got a vice, might know someone....it's annoying me. need to seperate the pedals from the cranks too, and they are also seized on..