hit-for-pass clarification

[kioto mitsubisi]

Hi,

I am testing Varnish and really liked it. Thanks a lot for this great software.
While reading documentation and mailing-lists, I got confused by the concept of hit-for-pass.
When there is no cache object, Varnish will queue the incoming objects and send only one request to the backend,
and return the result. However if the response from backend is not cacheable, then a hit-for-pass object is generated and all the request will go directly to the backend. My question is that the given example for this scenario is response with set-cookie header. However, I put the following line in vecl_recv to remove cookies.

    unset req.http.cookie;

So in this case, if backend returns a response with set-cookie, will there be a hit-for-pass? Do I need to remove set-cookie in vcl_backend_response in order to prevent that? Could you please help me to understand the concept?

Thanks in advance