Periscope's SQL Snippets can be used to create a simple string of SQL that can be reused in as many charts as desired.
Start by hovering over the "SQL Snippets" menu item in the header:
From here, hover over the "+" button in the top of the SQL snippets menu to make a new snippet:
Make a snippet called user_is_real that will filter out spambots, admins, and deleted users in all of the charts.
Simply type the SQL in the box and click save:
A description can be added to the SQL Snippet to inform other users of its purpose.
To use the snippet in a chart, put the name of the snippet inside square brackets where the snippet's contents will be substituted into the query:
Use the snippet [user_is_real] here in a graph of users over time:
At any time, hover the mouse over the snippet to see its definition: