And some holders of IP's are MUCH more likely to think "My precious... Nasty, thieving hobbitses has stolen it" and then go full Smaug on Lake Town than others are.
Yeah, I think it's tricky, depends probably on how much people care. I remember when Carlton from Fresh Prince tried to sue some video game company over his "Carlton Dance" he made famous in that show, but they were like "nope, just dance moves, you don't own those" and dismissed the case.
And I remember hearing Matthew McC (I don't know how to spell his name) specifically copywrote "Alright, alright, alright" so literally no one can use that specific phrase without getting in trouble. I feel if he went to that much trouble, if you used that, he actually WOULD do something about it.
If you wanted to be REALLY safe, you could probably just change one word. I was reading up on patents on clothing and apparently some of that stuff is really tricky. You make a green with some white design. You can't patent every single design, so if a person really wanted to copy your dress, all they had to do was change the color by like 1 shade and the white design ever so slightly and it was technically a new dress.
I know none of that probably helped, hah.
On a side note, my favorite Futurama quote is regarding Slurm: "How does it taste? It varies from person to person."