An advance review by James Montgomery of MTV stated this was their most brilliant album. Michael Menachem of Billboard fell in favor of the album, saying "If you don't finish this party record a hot mess, then you probably didn't have a good time." Tim Sendra of AllMusic called Hot Mess "a complete success and shows that the band could possibly grow past the comedy and become something else entirely." Daniel Brockman of The Phoenix gave a generally positive review, stating, "Only a music fan obsessed with the rules of authenticity and the requirements for lyrical profundity could find fault with the 11 odes to overload that make up Hot Mess." Mikael Wood of Spin raved that "Hot Mess is flush with other stupid-smart highlights, including 'Pete Wentz Is the Only Reason We're Famous."Rolling Stone's Christian Hoard said that "Sometimes the former Midtown singer's snark falls flat, as with the title 'Pete Wentz Is the Only Reason We're Famous' or the part where the singer brags about his ass. But Saporta does have some pop gifts, apparent on the disco 'Living in the Sky with Diamonds.'" Edna Gundersen of USA Today gave the album three stars out of four and stated: "While unquestionably accessible, Cobra's retro, overly flashy Swedish-leaning pop isn't for everyone. It's daft, it's dorky, it's discofied, but it's also deliciously fun and kitschy."
Bill Lamb of About.com gave the album 4/5 stars, using a comparison to praise; "You went digging around in your parents closet of old vinyl LP's from the 80's, found one with candy-coated colors on the cover, played it on their old turntable and discovered it really wasn't bad. Then a few days later after listening to it for the 15th time you realized you had fallen in love with the goofy, fun, sarcastic music. It's quite possible it sounded a lot like Cobra Starship's Hot Mess."
By October 2009, the album's sales stood at 80,000.