Approaching day job's customers about startup?
_delirium: What kind of customers are we talking about? I think it's more likely to run into trouble if the customers are themselves large companies. If the customers are small---individuals or mom-and-pop restaurants or something---it's probably easier to reuse the contacts. That's just a guess, though. The current company would probably not be happy about it either way (though that's not necessarily determinative, because companies are unhappy about anything that remotely smells like competition, regardless of whether it's ethical or not).