Someone posted a good comment on WD this morning, not on a poem of mine - I haven't posted one since The Old Tart - but this could help when I'm dissatisfied with things.
'...don't expect every poem to be better than the one before. Few poets are consistently good. Some of the best produced very ordinary stuff along with their brilliant work.'
It fits in well with Stephen King's advice that you need to be there working regularly, to stand a chance of the Muse dropping by.