Question

I am using a link on my site name “sign_up”. When you click on sign it, it checks what language you have selected and what curreny, and permanently redirects you to the correct page using a 301 redirect.

Is this bad for SEO? Keep in mind, this is the way it will remain. I’m not eventually going to get rid of it?

Answer 1

The HTTP 301 status code makes no sense at all in this case because you are performing a redirection based on client settings and preferences.
How would the crawler know which is the right environment?

Take the following screnario

client A connects to /signup with preferences X 
=> 301 to /en/signup
client B connects to /signup with preferences Y 
=> 301 to /it/signup
client C connects to /signup with preferences X
=> 301 to /en/signup

Which would be the winner? Nobody.
A 301 makes sense only when an URI uniquely and permanently redirects to an other location.

Additionally, trying such kind of optimization for a signup page IMHO seems to be a little insane. Many SEOs are used to exclude the signup page and similar pages via nofollow attribute.