Wearing the tax debacle, for sure. Here's a few others they'll wear:

failed electoral reform debacle
failed to meaningfully amend bill c51
failed defence procurement
deficits well above promises
no promised infrastructure, anywhere. Where is that infrastructure bank, BTW?
climate change goals no different than harpers
cost of hundreds of useless delegates to paris climate conference
cash for access
failed energy east pipeline
disgusting hand out of $10 million to omar Khadr
Melanie Joly's bomb on 'culture'
Butts and telford's outrageous moving expenses
thousands of  presumed haitian refugees flooding across the border
a lying defence minister, a bumbling weasling finance minister, several other awful ministers 

so much more ....