If you are making a claim about the general, broad pattern of something, such as "the media tilts left", then a lefty can debunk that claim by finding 1, 2, 3, ... up to, oh, let's say, at most, 7 counterexamples. A finite number of counterexamples is always enough to disprove a conservative's claim of general tilt.
For example they can say "Fox News" and often that's enough. Or they can point to some column published in a Laramie, Wyoming newspaper. This counter-argument concludes by smirking and saying "see! what liberal media?" A convenient shorthand is to link to one non-liberal-tilted column/story, or even just a story that contains negative news about a Democrat, and say "here's an example of the So-Called Liberal Media". They've even abbreviated it (SCLM) which is very clever.
For example, what follows constitutes a valid lefty counter-argument to the notion that the media tilts liberal:
"Here's the SCLM in action folks!!"
And that's that. For the master at this kind of "argument", I highly recommend the web-log of Oliver Willis, who seems to specialize in it. For example (I'm not making this up!) I just checked over there and here's his latest post, in its entirety:
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"Liberal Media"
Submitted by Oliver Willis on Thu, 09/02/2004 - 3:35pm.
Bush's war-on-terror flip received far less coverage than Heinz Kerry's "shove it" comment
*Sigh*
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(The original contribution of the author, Oliver Willis, to this post, of course, is "*Sigh*".)
So, I assume the same rules will apply here for the Hollywood case: the general claim "Hollywood leans left" can be refuted simply by listing some (a finite # of) people in Hollywood who don't. Since they can point to Schwarzenegger, Gibson, Bruce Willis, Kurt Russell, James Woods, Bo Derek, and (well I'm running out of names off the top of my head) a few more examples of known Hollywood folks who aren't out and out lefties, that will be enough to disprove the whole notion.
I'm just telling you this so you can be prepared.