What does it mean for SVN "to polute the local source tree"?
I'm reading "Professional Team Foundation Server 2010" by Wrox, and in an advantages/disadvantages list, the said:

"Like CVS, SVN makes use of .svn directories inside the source folders to store state of the local working copy, and to allow synchronization with the server. However, it can have the affect of polluting the local source tree, and can cause performance issues wiht very large projects or files."

What does the bit about pollution mean? I've used SVN for C# & ASP.NET projects for a long time and haven't encountered any problems.  What probably does this quote think I should have been watching out for?
What does it mean for SVN "to polute the local source tree"?
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I'm reading "Professional Team Foundation Server 2010" by Wrox, and in an advantages/disadvantages list, the said:

"Like CVS, SVN makes use of .svn directories inside the source folders to store state of the local working copy, and to allow synchronization with the server. However, it can have the affect of polluting the local source tree, and can cause performance issues wiht very large projects or files."

What does the bit about pollution mean? I've used SVN for C# & ASP.NET projects for a long time and haven't encountered any problems.  What probably does this quote think I should have been watching out for?