How long is too long for someone to vanish ?

I recently had someone approach me about modifying a script of theirs to work with Amazons S3 cloud storage service. since I'd never worked with S3 before and it seemed intersting, I told them I would have a working demo by the morning since it was a weekend night and it was agreed. I indeed did have a working demo before the sun came up.

I didn't see online or hear from this person again for two days, so I took down the virtual host I had setup with the demo on it and forgot about it. Three days later they contact me and ask if I have anything ready again mentioning how they need to get it done ASAP.

One of the guys I worked for as a teenager used to have a saying, "No call, no show, no job.", and he loved to fire people who were nowhere to be found on a day they were supposed to work, which makes sense to me on either end, so I've just not been reading this new guys emails anymore.

So, what do you think is an acceptable amount of time someone can just vanish before it's a good idea to write them off ?
Of course excluding situations involving doctors notes and bail bondsmen.

How long has it been since the second time he contacted you? If he seems flaky, I'd drop him now.

I hate people who want things ASAP and then when you do the job for them in double quick time you spend 10 times more time trying to track them down............. that said, I guess I give about a week generally before I cross people off the list.... on the other thing I've had jobs drag for years, where I didn't expect a profit and people couldn't get their act together....

There was a time I would wait everyone and anyone out, and eventually they almost always came through, eventually.

I'm just sick of waiting for people and online it takes a lot less time to find new business that has their act together than it does to hope someone will get back to you in a timely fashion.

If it makes you feel any better, about 6 or 7 months ago I was working with a support guy from some rinky-dink fly-by-night software company that wrote an application for our engineering department (and it didn't work for *plum*) and all of a sudden my emails to him were being bounced back and when I would dial his direct phone number it said it was disconnected, so I got a hold of the other half of this company (yes, only 2 people) and the dude told me that his partner just up and moved away, quitting the business for no reason on the spur of the moment. Hows that for vanishing? He did end up fixing the problem that the first guy said couldn't be fixed, so maybe that had something to do with it.