Is that T-shirt from Coinomize.biz? Wow!!! Nice one. But scammers can produce things like this and when you scam it it will link to their site and if the design are similar then you won't know the official website so the best way to avoid all that is the signature from the participants. Because the signature is personally design by the company and scammers can change the code. Except the account is compromised.
This t-shirt is indeed good and limited edition, because I myself made the design and then printed it.
There is a project for Coinomize t-shirts that I have proposed in the past on the Bitcointalk Forum, and some people have also made them sponsored by Coinomize.
You will not find a scam link on the My QR Code T-shirt, but yes be careful it is necessary and don't trust anyone, it's better to double-check before entering any link.
Do most people click signature links though? Personally, rarely do that because I remember the clearnet link for most services that I used, used a bookmark, or double check with other sources like social media and so on. Some users might disable signatures visibility too so they definitely don't think signature links are how they access new services. I guess that's not really Coinomize problem to solve since there's no way to force them to view our signatures.
I also don't click on the link in the signature, but in any case the link in the signature must be correct because some people are interested and log in using the link in the signature. If there is an error or it is not an official link, then it is necessary to recheck. As you say, "
Being careful is not bad"