The OP will get away with pumping grow money into flipping houses until he is audited. If/when audit day comes, the OP is going directly to jail.
As someone mentioned, paying for services in cash, or pumping 'dirty money' into a clean business and liquidating that business by trying to sell it legitimately does not disguise your dirty financial paper trail. All it takes is a simple investigation into your financial history, ie) the source and amount of your 'declared' and taxable income (either personal or business) versus the amount you're spending (or have spent) and are worth in taxable assets. If you're spending more than you legitimately earn and declare (which is taxable), the IRS will find out when they start investigating, no doubt about it.
It isn't as easy as buying a cheap house, using undeclared cash to fix it up, and selling it for twice the value. Enter IRS Audit Man.. "Where did you get the cash to fix up this property? We understand you were given $50k as a legitimate cash gift from your late Granny Loadsofcash to pay for the purchase of the house, but we can't see how you've paid for this new kitchen, bathroom, electrical and plumping work, decorating, ... when it says here that you're only earning $20k a year after tax. Can you explain this to us, Sir?" Expect that question to be asked if you're ever audited.
Like I said, you'll get away with it until someone bothers to check what you're doing. Good luck.