I disagree with steve cm because the round is what you make it-if the work is there paperwork doesnt really matter because your buying the work not the business-you are not taking on any debts but your own
its all about the history! no history then your easily ripped off arn't you? :

if you have a decent paper trail, you can work out what overheads etc you need. we all keep our overheads high to stop the tax man taking to much. You just need to see wether it makes money?!
also if you want to go to your bank for decent funding to buy a business then they will probably ask to see its accounts.
would you buy a car with no history or paperwork? i wouldn't your to easily mugged off. same rules apply here
I've bought work i've taken a punt at as it was cheap to buy but if your talking a proper business with proper accounts then your gonna get more arn't you? I would buy out a competitor for a decent amount in my area if i could see they have a proper business.