From experience, I woul say no.
Keep in mind that total traffic and error traffic increased, and hosting costs decreased... my three years of running a freehost went like this:
First year - nice profit
Second year - broke even
Third year - actually lost money
Freehosts were, and probably still are, cheater magnets. You'll get spam complaints, C&D letters up the ass because people will use stolen content, pedos spreading their garbage, Japanese warez fiends hammering your box and everything else you can think of.
Kill the cheaters accoun't, get attacked for it. Redirect crap countries, get banned at the only TGPs and LLs that have any traffic...
The 404 traffic can still be valuable, regardless of what others may think... but once a freehost starts doing 1/4 million pages views or so, babysitting it can become a full time job. blah.
If you want to attract "real" webmasters, you'll have to offer subdomains at a minimum, domain hosting preferable. If this is the sort of customer you want, you will HAVE to use header and / or footer ads.
If the error traffic is your goal, you actually want cheaters. Huh? That's right, you want cheaters and you want them to build up some traffic before you pull the plug on them and redirect the shit.
404 traffic is the only real way to make money with a freehost - "honestly" getting enough of it to pay for things is the tricky part.
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