IANAL, this is just how I've always understood how the system works here in Finland, and I don't see the loophole in it:
To give bonuses in the first place, you first have to get money from somewhere. And whatever source a company is getting the money from, it would be wise for the source to make definite preconditions for the loan money. And if that money is still used for something else entirely (like say, CEO bonuses), then it's a breach of contract, and thus could give a basis for a personal liability.
In other words, if I started a company, took customers' money that they paid for products, then ignored running the business and instead used that said money directly to give myself bonuses, I would be a viable target for fraud charges, as I would be simply siphoning money under the pretense of a company.
If, on the other hand, the business is booming, I can collect sizeable bonuses. And if I buy something extra for myself with my bonus money (that's already on my own bank account), and decide to freely loan it back to the company's benefit, then no biggie. But on the contrary, if I bought a car under the company's name, and didn't register it as a "job perk" (fringe benefit, counted as taxable form of income), but still used it mainly for personal stuff, it could fall under a scrutiny. Main reason for this is that the companies can deduct part of the purchases in taxation. Using this for your own personal benefit is illegal. There are also comparable rules for bribery; if you're working for a big company, and you're the one choosing a supplier from a group of five companies, you can't legally accept any sizeable gifts from these companies (pens or a cup of coffee are OK, opera tickets are already on the edge).
And sure enough, if there are some oddities in the accounting (which are mandatory to file), they will be under a stricter scrutnity. For example, if I sell an office building for 500€ to myself or a friend, some alarms might set off with the authorities.
Though related to this: if you're under an investigation, then your personal property (like a work desk or briefcase with the company stuff in it) can be seized for the duration of the investigation, if it can be seen as a likely evidence.