I applied for multiple visas before (not US visa), but all of them was from my residence country. In all of these cases, I can get official paper which support my evidence (bank statement, letter which states I am employed with high salary, marriage certificate, security clearance, ...).
It is the same question as Can I apply for and receive a US visa when residing in country other than my own?, but I am not residing; I have a business visa.
case-specific details: I am from Egypt, I have business visa for Ireland. While in Ireland, I want to apply for US business visa.
Why no to apply from Egypt?: Because waiting time is too long (75 days). Waiting time in Ireland in only 18 days. Both visits (Ireland, US) are short visits (3 weeks for each).