Land flippers sent out direct mailers with blind offer

[May Lin]

Hi Professionals, as a land flipper in FL, we send out thousands of direct mailers with blind offer, when seller calls back, we negotiate the price due to some material facts of the land, did not honor the offer price we sent initially.   Is it illegal,  not ethical, violation, red flag or fraud? or grey area? or anything wrong business practice? 

[Kristi K.]

Quote from @May Lin:

when seller calls back, we negotiate the price due to some material facts of the land, did not honor the offer price we sent initially.   Is it illegal,  not ethical, violation, red flag or fraud? or grey area? or anything wrong business practice? 

It is legal? As @Account Closed says, yes until a contract is signed. Is it ethical? I think you know the answer.