It's not an idiom. An idiom makes no sense unless you know the meaning. When you use AS (or like) ____ you are using A Simile, which is a comparison. This is comparing someone's smell to that of a rose.
The idiom "smells like a rose" means that something appears favorable or promising, similar to the pleasant scent of a rose. It suggests that a situation is likely to turn out well or is free from any issues.
The term "smelling like a rose" refers to someone/something that smells nice.
"Smell like a rose" isn't an idiom because it means just what it looks like it means. You are comparing someone's smell to that of a rose. Comparisons with AS or LIKE are Similes.
it smells amazing for some and bad for other
perfume rose
"It depends on the name of the fragrance. If you're looking for Channel No. 5 most people say it smells like a floral arrangement but can never just say it smells like just a rose, a lotus, ect."
a rose that smells just as sweet shekspear
Imagine someone smelling like a rose -- this phrase means that no matter what the person does, the "stink" of doing bad things never seems to stick to them, and they "smell" good all the time to the people in charge. If your coworker never gets caught stealing office supplies, you might say "he's a thief, but he always comes up smelling like a rose."
not that much but rose smells good
The actual title for this nursury rhyme is simply "A Rose" and it goes like this: A Rose Rose, rose, pick a rose, A rose smells so sweet; Roses are red, pink and white, They are so nice and bright.
I'm pretty sure the element you're thinking of is Uranium, because geranium is a flower, that smells almost like a rose.
The sentence in passive voice would be: "Sweet is smelled by the rose."
It means "like a rose" and is an informal version of the name Rose.