system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:How does money laundering work and how do some people get away with it while others get caught.
gpt
Suppose you make $100k a month selling ... something bad. You can't deposit that money directly in the bank, because large cash deposits require special forms & draw IRS attention (and, if it is suspicious, eventually the police). 

But, let's say you also happen to own a car wash. That is a business where people primarily pay cash. Now you can deposit your "bad" money and claim that you made that money at your car wash. It works great, but of course it looks like your car wash is much more profitable than it actually is.

This is how you get caught. The cops start to notice that you're depositing lots money (and claiming on your tax returns huge profits). In fact, they calculate from your taxes that you wash 10 thousand cars a month. BUT, they check & find out that you're only ordering enough soap & supplies for 3 thousand cars. This is a huge indication that the money you're depositing is not coming from the car wash. 

In order to NOT get caught, you need to have a pretty successful cash businesses so your bad money won't be noticed. Big banks often get away with this, because they have such huge profits that a little bad money won't be noticed. 

Or, you could always bribe/threaten/etc whomever is investigating you...