In what situations do you think is not OK to pirate something?
Never pay money for pirated content or ask someone to pay money for pirated content. Donations to keep a site running are borderline and iffy, depending on the implementation and transparency. As soon as you earn any kind of revenue or treat it as your 'job' it crosses into the unethical IMO.
Second point related to money: Pirating stuff you could easily pay for is probably bad, if the creator receives $0 from you. There might still be reasons to do so (not wanting to support DRM for example), but if you got the cash you better find a way to support the actual creators (merch, donations...). The smaller the author the heavier the moral responsibility to bring some money their way. This also weighs in the other direction: It's probably accetpable or even good to not give more money to giant corporations that abuse intellectual property for their own gains and who shit on creators.