When website design agencies write a website for a client, they usually place a hyperlink on the footer of the website back to their own website i.e. 'Website Designed by XYZ'. If this footer exists on Every page of the website, how does Google perceive this? Would it help, in terms of Inbound Links, would the site be penalised, doesn't it matter or the agencies better off only placing the Website Designed by.. once on the home page?