Accrual based accounting is a tool which can be used for good or evil. Some companies want to maximize their profit, because that makes them able to pay good salaries, large bonuses, and makes them attractive to investors and lendors if they need to get more cash. Other companies, believe it or not, want to minimize their profits because they have to pay taxes on them. So they hide away the actual profit in a maze of future expenses and bad debt estimates.
Occurrences of outright fraud are actually rare - but they are usually spectacular when they do occur. Enron was an accounting fraud, for example. But instances of optimistic accounting are commonplace.
