My cousin's father-in-law owns a chain of car wash on the East coast. They have a good bottom line, but its all about location, as some do way better than others. Its also a capital intensive business.
If you're looking for a good side biz, I've know quite a few people who have done well with candy machines and game machines. Those kind where you pay .25 cents for one gumball. Know one fellow who had video games in a whole lot of 7-11's and he went out in a pickup truck a couple times each month to pick up all his quarters and averaged about $15K a month.
Payphones where good for a while til cell phones took over.
Best side business I know of is Real Estate. Buy fixer uppers or properties about to be foreclosed on way below market and throw $20K to spruce them up and you should be able to make a nice profit.
Mail order is always good, but you need a great idea.
Also have an uncle that has 15 of those mini-donut systems at malls, swap meets, etc, and he's become a millionaire from them.
Big markup on those suckers I guess.
Good Luck $!
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