Is dobutamine stress safe in someone with cocaine chest pain?

Probably. As long as the patient did not have an actual infarct and was not having serious arrhythmias, I wouldn't necessarily have a problem using dobutamine. Exercise or Adenosine (or regadenoson) would be my preferred choices, however.
Generally safe. It has its risks of causing arrhythmias, chest pain in any individual. Whether Cocaine induced or atherosclerosis.
Stress tests. If chest pain is active further evaluation & blood tests for myocardial damage is indicated as well. But tell doctor Cocaine has been used because beta blockers can lead to unopposed Alpha adrenergic activity with potential disastrous consequences.