Making offers site unseen. How?

[Jon C.]

I am looking into Hud properties and already spoke to an agent willing to submit offers repeatedly for me. In general, for any listed property, I have read several investors who say they make 10, 20+ offers a day. There's no way all these homes are walked through prior to an offer. Is there some basic formula used to determine an offer that takes into account rehab without actually seeing the property? For example, I've heard some people will multiply the square footage by anything from 10-20 depending on basic observations of the condition to get a rough number for rehab. Any other methods?