sure, it can and is used for laundering, but that is not the only purpose. also, the more people that join into bitcoin, the more that use these services for more ethical reasons.
the actual truth is that any one that has a real need to launder funds and knows what they are doing will be doing it themselves and not using services like these. you are traced and tracked in more ways than just the address and these services likely get more people caught than they protect. the big case of laundering that got the silk road interrupted was cloaked by some mixing and tumbling, but it was not enough. the most common secondary tracking method is endpoint amount tracing. if the FBI knows that i received $10,000 for an illegal activity and that i was likely paid within this calendar week, then they can find the start point, you can even do that. simply search for TX's of that amount in the date range. the list will be pretty small and you can narrow it down with a little research
so, they see the original TX and then i throw it into tumbling and mixing. the FBI software takes 16.38 BTC and prints a pyramid shaped cone, the overall fee for a TX at level 1 for 16.38 is 0.01638. TX fees are percentage based, so even if that is split between 10 TX's the amount is the same. the software iterated outward for ten or so TX's, printing the results at each level and you have a simple chart that tells you how much is left from the base number after 1, 2, 3.....numbers of TX's.
so, you want your funds back in one or two accounts after laundering. let's say you used a tumbling service, it took in 16.38, went through several accounts and spit out 16 to your other "clean" account. the fbi software will show that after say "5" TX's the original 16.38 is now 16.2, the software reads like this.
Level 5 TX's 16.2 left after TX fees, 16 after TX fees+common tumbling fee
and there you are, one of maybe 50 addresses that received 16 BTC one week after the alleged paid crime. They are watching for that amount and ten other amounts based on the software, plus amounts that are one half and one third those amounts. it is all on one piece of paper, i have seen it. you end up as one of maybe 1000 TX's meeting those criteria, but then other software purges a bunch based on other factors, common addresses and such. that is how Interpol closed that money laundering case and put the silk road in the lime light.
it is like triangulating position, the first laundered TX and you might be part of ten suspects, once you do it a second time, it is all over. there are much better ways to attain absolute anonymity and tumbling helps, but it is just one tool in a larger system
Learnt much knowledge from your post, it seems like mixing service is not very safe, how about monero or dash for them? More anonymous than mixer?
