Can't use a normal work in Gamertag?

I understand perfectly your point, just try to combine the gamertag you want with another word or character, I tested with "Blood1" and the availability allowed me to choose it.

Hello!

I'm a Independent Advisor. I will be glad to help you.

If it does not allow you to use a certain gamertag it means that it may be considered offensive or may violate Microsoft Service Agreements or community standards, you can check them out at these links:

https://www.microsoft.com/en/servicesagreement/

https://www.xbox.com/legal/community-standards

Best regards.

Why wouldn't they give specific information on what's ok and what's not? I understand profanity as it's not ok at anytime but blood? It's like bones or skull. Like it was usable as there are gamertags with blood in it but not now? It's just so odd and hamless I wounder how far microsoft will take it.

Microsoft does not give specific information about which words are not allowed or why they are not allowed. You could try a combination of other words and characters, there should be no problem with that, but by itself the word "Blood" is not allowed by the system to be used as a gamertag.

If the system says the tag is taken then it's in use somewhere on Microsoft's servers. The tag system is in use on other Microsoft services so even if it's not being used for Xbox it could be in use elsewhere. The system also doesn't see things like spaces
as making a gamertag unique. So you could look up "gamertag" and it may not show up, but could still be in use as "gamer tag"