Should client sub domains appear in Google or not?

[muzzmoz]

I have a client who has created a number of login pages for their clients (eg. clientA.domain.com, clientB.domain.com). They are all password protected.

Just wondering if this has any impact on SEO, good or bad?

[muzzmoz]

Yeah, that's the next step. The robots.txt file is blank!

[Roman-Delcarmen]

As seoman10 mentioned, you or your client don't have to worry as long you set up the Robot.txt file properly

[seoman10]

Obviously I don't know the exact structure of your site, but I can't see any difficulties with SEO.  I doubt any content behind a password would be found, the only thing to consider is the login page, depending on the use you could block it in robots.txt.

I think mostly Google see subdomains as different sites, depending on how they are linked together.  You want to be careful that people can't publish spam on the subdomain this could hurt the overall reputation.

If you want to completely stop Google crawling the subdomains you could implement HTTP basic authentication, This loads before the page is even visible.