netstat wont create any outbound ethernet traffic. As explained nicely in RFC 1147, netstat is...

...a program that accesses network related data structures within the kernel, then provides an ASCII format at the terminal. Netstat can provide reports on the routing table, TCP connections, TCP and UDP "listens," and protocol memory management

So running netstat in a loop wont bring your local sysadmin running for the reason you cite. Obviously, running anything in a loop without care may cause other problems.

cheers,
Anth