It's harmless to rely on these reports even if they are inaccurate because there's no consequences for users who are mistakenly identified as "tainted".
The consequence is that they can't use the software they downloaded and installed for the purpose they intended. The software that is free and open-source.
You can't possibly know what other consequences there could be. Blockchain analysis now has those coins on their radar, and will surely follow the money to try and identify the users. This creates a problem not only for the person that got banned from coinjoining, but anyone else who might purchase those coins in the future. Those "tainted" coins could be bought by someone who later deposits them on a KYCed exchange or similar service and bam, they will get frozen and maybe confiscated. Then it's up to that innocent individual to prove his innocence.