The 24-year-old has managed to secure a singing slot every Tuesday at The Sayers Club in Los Angeles not because of her singing prowess but due to her star appeal, reported online media.
"The venue likes Rumer to sing every week because she brings publicity but the truth is she's horrible," a source said.
The "House Bunny" actress, who has also appeared as a guest star in TV shows like 'CSI: NY' and '90210', however she remains oblivious to the criticism and is determined to build a music career.
Rumer believes she sounds like singer-songwriter Lana Del Rey, maker of one of the best selling albums of 2012 'Born to Die.'
"The regulars all secretly laugh at her because she is always bragging that she sounds like Lana Del Rey when actually the audience can't stand to listen to her.
"Rumer is a chain smoker and she feels like smoking gives her voice a raspier edge like Lana's. But all it really does is cause her to cough constantly on stage which adds to her poor performance," the source added.