For example, a promise of the form, "I will give you ten dollars if I feel like it," is purely illusory and will not be enforced as a contract.
However, courts will generally imply in law that the promisor must act in good faith and reject the deal only if he is genuinely dissatisfied.
However, courts may find that the promisor made an implied promise to use reasonable efforts to try to make money, and cite him for breach of contract if he does absolutely nothing.
Of course, if the promisor entered into the relationship purely with the intent of fraudulently harming the promisee, he could be cited for fraud or bad faith principles that apply to all contracts.
[5][6] In Douglas v. U.S. District Court ex rel Talk America, the court found a telephone service provider could not change the terms of its service contract by merely posting a revised contract on its website because "an offeree cannot assent to an offer unless he knows of its existence."