Learn English – English expression for “ascribing negative intentions to someone”

I guess you mean 'difficult to locate/find', rather than 'rare'. The commonest idiom for objects difficult to locate is needle in a haystack.

Red cars, for the man, were like needles in a haystack.

This means the man found red cars very difficult to spot.

There are several related idioms for things that are hard to chance upon. A couple of them (also mentioned here):

• scarce as hen's teeth
• black cat in a coal cellar

An expression that gives me a not entirely healthy satisfaction and which I'll offer is:

He bit the dust.

It's a very old phrase that means "he died", but it just sounds so damn pathetic.

EDIT: This just occurred to me after seeing the f-bombs dropped in the comments. I remember that Tommy and Turkish in the movie "Snatch" use the expression

He got proper fucked

to refer to someone who's been killed. Actually, here they're referring to a rabbit, but the idea's the same. Urban Dictionary has a definition that doesn't do a whole lot of good, but it supports the idea that to be fucked could be bad, but to be proper fucked is terminal.

This term, to the best of my knowledge, is strictly British English.