If you asking if somethings flippable you shouldnt be flipping.
1. NO rust.
2. Complete bikes are a must.
3. Know your product.
4. Know your market.
5. Be prepared to lose money on some bikes.
I have drasticly different prices I'm willing to pay based on the quality level of the bike. Certain bikes I avoid like the plaque. Those would be all mountain bike and all non-bike store bikes. I also avoid anything from the last 10-15 years as they're a dime a dozen and not very collectible.
One of the most important things I consider is parting out value. If my 'flip' turns into a 'flop' can I part it out and recoup my money? Some bikes I buy with the sole intention of parting out.