Well, first, I'm going to refer you to this:
http://en.wikipedia.org/wiki/Betteridge's_law_of_headlines 
And then I'll address your questions more seriously.
If I said Michael Bay was my favorite director (he is most certainly not) would you regard my further opinions on movies differently? Wouldn't you take that information into consideration when evaluating how much stock to put in my opinions of movies?
I would, yes. I would think that your tastes and mine are unlikely to overlap. It would depend, however, on why you liked his stuff. If you liked it because you literally just wanted to see images of robots fighting and things exploding and stuff, and you knew -- and didn't care -- that the film was otherwise offensive and/or incoherent, I could respect that, even if I didn't agree with it. I mean, I love watching awful, cheesy films like
Remo Williams: The Adventure Begins! and
Gymkata and other similarly bad films. I love them because they're absurd and terrible and hysterical, and that entertains me. So if you love you some Michael Bay films on a similar level, hey, that's cool. Different strokes and all.
But if you think his movies are qualitatively
good, then we have a problem.
Aren't polarizing subjects like Michael Bay and the Star Wars prequels actually a good indicator of identifying like minded people, and wouldn't you value their opinions a little more or less accordingly?
To a degree, yes. A person's appreciation of this or that producer/director/style of film can be an indicator of their tastes. But it's not always 100% reliable. For example, I just mentioned that I love dumb action movies from the 80s. If that was mostly all you knew about my tastes in film, it might surprise you to know that I've been watching my way through -- and loving -- a series of BBC teleplays of Shakespeare's histories, beginning with Richard II and working their way through Richard III in order of king's reign (Richard II, Henry IV parts 1 and 2, Henry V, Henry VI parts 1-3, Richard III). It's basically the Shakespearean version of the Wars of the Roses and it's AWESOME. So, one's taste in one area isn't always indicative of their tastes in other areas.
I think a better indicator of someone's tastes is their reasons behind their enjoyment. And as for whether I can agree with someone or at least get along with them in this setting, that often depends on how well they can explain their position, and how respectfully they can state their opinions.
Should fans of Michael Bay feel attacked personally over some of the harsh words in this thread?
Generally, no. Attacking Michael Bay isn't the same thing as attacking Michael Bay fans. Although, it depends again on why/how they enjoy his films. Again, if you're of the opinion that his stuff is just entertaining fluff, on a certain level, I say "Rock on." Enjoy yourself your way, and I'll enjoy myself my way. If you try to argue that Michael Bay is a good story teller, I will gladly debate you and prove you wrong.
But that raises a related issue about internet discussions and such. Very often, people identify
personally with this or that bit of entertainment or this or that creator (Michael Bay, George Lucas, JJ Abrams, Chris Nolan, etc.). Their fandom runs deep enough that it forms a portion of their identity, to the point where if you attack the object of their fandom, you attack them. I have very little patience or time for arguments with folks like this, for two reasons. First, it gets exhausting trying to explain -- again -- that I'm not saying
they're an idiot for liking this or that, but rather that I think the thing they like
itself is idiotic, which is not the same thing. Second, because folks like that lack the ability to distinguish between "playing the ball" and "playing the man," they typically resort to abusive ad hominem arguments. I don't respect people who do this. Moreover, their attacks eventually either exhaust me or get me to a point where I lose my patience and lash out at them, typically in a fairly blistering way, and all that does is poison what could otherwise be pleasant discussions online.
Anyway, the one thing I'd say about Michael Bay and Michael Bay fans is this. My ultimate problem with guys like Michael Bay is that they are fundamentally lazy. Personally, I think it is possible to make films that speak both to people who want a coherent story, and to people who want a spectacle. The two are not mutually exclusive. But when guys like Michael Bay succeed, all it tells the suits is "Keep up the good (crappy) work." It tells them they don't HAVE to try, because even with racist robot caricatures, and robot testicles, and statutory rape jokes, even with completely incoherent or contradictory or continuity-destroying plot points, people don't care as long as you show them explosions, robots punching each other, and the occasional slow-mo pan of military hardware or a girl's T and/or A. I encourage people who want a big spectacle to be more discerning with their dollars and to spend them on stuff that gives them a spectacle AND an entertaining story, rather than just the one at the expense of the other.
