No, I don't check serial numbers. The difference here is, the systems at play with crypto are not the same as you giving some cash to a cashier or whatever. There is not some realtime global database on every payment. Also, cash in general, is used by regular people, grandmas etc. It doesn't have a bad rep (increasingly lately.. but in general, it is seen as normal). If you are a "Bitcoin person" you are standing out from the rest already. And governments hate crypto by default, banks do so too. This is why they block transactions all the time, even with KYC exchanges. So it's not the same thing at all. They will find any excuse to extract as much money as possible from you and scare you from using it. I am not looking forward to be used as an example of that. And as far as Monero, we can see what happened. It was kicked from most exchanges, you cannot cash out Monero to buy anything of relevance.
Genuine question; then why would Bitcoin be in the discussion at all?
If your government is fond of their citizens using Bitcoin, then they would find and make up reasons to find fault with you. Even if there is zero taint, I'm sure there is a good reason why they should arrest you and throw you into jail. If you are afraid that there is a possibility that this would happen to you, stick to fiat. Else, if you are aware of your rights and understand how the law operates, I don't see how this would be an issue at all.
Otherwise, if you are afraid that exchanges would find fault with you, or whoever you're transacting with, then you should stick to fiat and PayPal. Zero taint doesn't exist, unless you are willing to pay a premium in exchange for freshly minted coins. You would probably have to declare your income source as well, I don't think it is worth the hassle and the paranoia for you.