Q:

ASP.NET production websites that are SVN working copies

Is it good practice to have a production (live) asp.net website that is also a working copy to push updates?

A:

In general this is considered bad practice primarily because the source control repository contains the source whereas the production application contains the result.  The two are kept separate for a number of reasons:

Security.  If your source is on your production server, it's at risk of being viewed.  Maybe this is a problem, maybe it's not.  The safe approach is to just not have the source on the production server.
Performance.  The result of building the source can be optimized for performance in ways that the source itself generally isn't.  In a .NET application, for example, the production deployment doesn't contain debugging symbols.  This may not be an issue in your particular application, but it's something to consider.
Multiple Results.  Is your source an actual application, or is it information used to build an application?  Can multiple versions be built?  For example, in a .NET web application, you might have Web.config transforms.  These are used at deploy-time to adjust the result of building the source.  If the source itself is being used as the live application, these deploy-time modifications aren't available.

Others may be able to articulate this much better than I can, but in general it is considered bad practice, yes.  Your particular application may be an exception to any particular reason or may not be meaningfully affected by any particular reason, so I stress the "in general" part.

