I am just trying to know from forum members if there is anyone who has ever had their bitcoin payments from signature advertising get blocked by an exchange, citing "suspicious transaction"?
Can we assume from this question that it happened to you? And if it did, tell us the name of the exchange so that other members can avoid using it.
What was/would be your course of action if they asked for source of funds or proof of source of funds, especially if you were dealing with payments from a bitcoin casino or bitcoin mixing platform (since most CEXs seems to be no so friendly with bitcoins from such platforms)?
If you insist on using that service in the future (you really shouldn't), just tell them where the funds come from. Tell them you are part of a signature campaign and those coins are payment for rendered services. I think that should be enough to get them to unfreeze your account, so you can withdraw your money. But they will probably lock your account after that.
I haven't faced any such problem so far. Currently I am using Kucoin for getting payment , And I have not completed kyc verification either.
Your signature payments go directly to an address owned by KuCoin? Why? How difficult can it be to create an Electrum wallet and be your own custodian?
I think if you choose good exchangers I don't think any such problem is likely.
All exchanges were good before shit happened. FTX was one of the best, remember?
But I would suggest that it is better not to keep large funds in centralized exchangers.
You should suggest that to yourself as well.
I remember with this thread
What Do Centralized Exchanges Consider as Taint? created by @Pmalek. If you look on this thread, there's many centralized exchange are not accept casino and mixer coins, but it can be solved if you send your KYC and other personal information to prove the source came from.
KYC doesn't prove the source of the funds. It proves who you are. If they were interested in how you earned that money, they should be satisfied if you proved to them that you are part of a signature campaign and get paid for promoting service X. Showing them the address where you get your service fees together with a signed message is enough proof. However, casinos want your KYC data, and they want it for other reasons.
I also suggest taking a look at this thread:
[Blacklist] of unreliable, 'taint proclaiming' Bitcoin services / exchanges