It's not difficult:
Entry level bikes sold as such = ok.
Entry level bikes sold as bespoke vintage hand-crafted track bike developed by deeply sexual Italian artisans and rolling on H+Son (I promise) and the slickest fixed gear finery = not ok.
Also not ok/damaging to reputation:
Selling mechanically unsound 'refurbishments'
Perversion of the great cycling lexicon to misrepresent products
Lying about Chinese manufacturers
Dressing up gas pipe and selling at BMC prices
Aggressive exchanges with forum members when called out on any of the above
For further info on unacceptable practices see Bad Traders thread.