He appears to be a smug opportunist and a swindler (prior to "A Flipmas Carol") where he manages to cheat each Loud sibling by giving them "Lily's blanket" in exchange for their garage sale money.
In "Out on a Limo", Lincoln states that he never gives him free smoothies, which means that Flip is stingy. This is also proven when he charges Papa Wheelie for double strawling his flippee.
In "Intern for the Worse", he comes between Lincoln and Clyde's friendship, by making them compete for higher ranking staff positions at his store, much to his advantage.
Flip is also a very repulsive man, as seen in "Intern for the Worse" where he sells expired milk, and uses the melted cheese machine to put his dirty clothes, mostly his socks. He also falsifies lottery tickets with a black marker. The oil he uses in his store was actually hot dog grease. His disgusting behavior is shown again in "Roadie to Nowhere", where he has so much gunk on his teeth which Rita tries to remove. He also has a false tooth made out of beef jerky.
He cares a lot for his profits, but has no regard for safety or lives of his customers, because in "Washed Up" he let Louds hire a broken boat from him. He blamed them for ruining it, despite it was his own fault. In addition, in "Snow Way Out", he would have abandoned the Loud children and Hops if not given the tickets, despite them being in danger of developing hypothermia.
In The Loud House Movie, he is shown to not like singing or pity parties as he kicks Lincoln off his property while he lamented about his sisters being more successful than him.
In "Much Ado About Noshing", Kotaro explains that Flip siphoned the drinks from Lynn's Table with his van but got livid when he was told give everything back. Later, Flip received an invitation to Lynn's Table as an attempt to see who the bad reviewer was.
Flip is a middle-aged man of short stature. He has gray hair, and a bald spot on the top of his head. He also has a gray mustache, and eyebrows as well. He wears a brown pants, black shoes, and a t-shirt that was originally white in Season 1, but changed to red from Season 2 onward. In "Intern for the Worse", he wears a red button-up shirt.
According to Lisa, Flip is the only person in town who will hire a four-year-old with no experience. It is unknown if this is true, or just part of Lincoln's fantasy.
The fact that he cuts corners, tampers with the expiration dates, and has unsanitary conditions with the food he sells, is similar to Apu from The Simpsons.
The fact that the slushies he sells have their own name, are similar to the Squishees, that Apu sells at the Kwik-E-Mart.
He received a slight redesign in "Intern for the Worse", and for that episode only, with that redesign featuring a slightly different shape to his facial features (prominently his nose and mustache), as well as other fine details added to the rest of his face.
Flip owns a Humvee, which he uses as a snow plow.
He has bad dental hygiene which he states that running his store was more urgent, and furthermore, according to Rita, his appointment has been ready for ten years.
In "Net Gains", it is highly likely he has been to prison before since one of the inmates recognized him as both he and Lynn were driving by.
He also runs a pawn shop business called 'Pat's Pawn and Prawn' and a ticket reselling business called 'Tucker's Tix and Tux'.
His great-great grandfather, Gip, founded the first ever business in Royal Woods, called "Gip's Girdles 'N' Garters".
Flip has impatience issues, as his struggles to fix the Flipee machine and nacho cheese machine completely aggravates him.
He was once a middle school delinquent and was in the same middle school as Lynn Sr.
Lincoln believes he is lactose intolerant, and he at least is in Lily's dream. However, it is unknown if this is true or if Lincoln and Lily just think it's true, since he's eaten cheese before with no problems.
He once got so angry that even his mustache turned red. 
When he sits on the Louds' dining room chairs, his butt falls asleep.
According to Clyde, Flip once threw out a kid for loitering while his mother was paying.