My take on this (the way we have been playing it in my group, at least) = is that Effect is something on a card (generally having the word "Action:..." in front of the actual effect wording) ..
If it says "Triggered Effect" - then it generally means one on a card that is already in play (like Slavering Gug's wounding ability where you pay 4, to choose and wound a target character) .... this is like what Brass Brady (Syndicate) is able to escape from (Shotgun Attachment, Prize Pistols, etc) - but NOT ...Action / Event - things like Short Fuse or Deep One Assault.
Anyways....on point with Performance Artist....yeah, her wording is overly general....and largely different from that of any other card, I think. You MIGHT assume (as Chris Long often asserts) that this is just another example of FFG being too vague and using widely varying phrases // terms - in descriptions for their cards, leading players to presume things about them that are different from how FFG "actually want them to be played".
On the idea that she can cancel even Passive Abilities....I would think this would not matter because once she hits the Discard Pile....the ability (passive) would resume again ....?
Example: A new Hastur card has been released. It is called "Insanity is Fun" - and is a Support / Enchantment spell that costs 3 to play. Its effect is to "Lower the cost to play any Hastur cards by 1, to a minimum of 1". That is a "Passive Effect" which does not cost you anything to "use" other than the original 3 resources you drained to play it in the first place.
You play this as your first action on Turn-3. Your opponent has a Performance Artist in play from Turn-1 or 2 and as soon as you play the "Insanity is Fun" card, they say they will sacrifice her to "cancel the effects"....
Now...technically, thanks to FFG's shoddy wording.....SOME players might try to argue the Cancellation effect is PERMANENT, since P-Artist's card never actually specifies when (if ever) the "cancellation" actually ends !
However...most players (since this card has been out for a while now) - seem to have always played it that it is a "one time Disrupt / effect", useful for stopping something like Deep One Rising's comes into play and destroys a target character - type of ability.
The idea that it could actually stop a Passive Ability would seem to fail, IMHO, because the moment you sac her to stop "Insanity is Fun" - in our example above, ....okay....that ability is "momentarily" disrupted.....now you place her in your Discard Pile. She is no longer in play.....instantly the Passive Ability "restarts" and continues to function normally again.
That seems how it would work in that example, at least, no ?