Infallibility is a function of office, not a charism of person.

I'm not talking about things that specifically happen during the liturgy, which are, unfortunately, frequently out of the control of the Pontiff, but of the idea of what the liturgy should be.

To illustrate, if someone is a liturgist who is advocating Communion in the hand and denigrating and deriding other legitimate options, like receiving on the tongue, or even receiving on the tongue while kneeling, I don't understand how that person could be described as an "excellent" liturgist.

Likewise with actual liturgical abuses, like ad libbing the Eucharistic Prayer in an attempt to make it more "relevant" to the assembly.

Forgive me if I'm sounding like Fr. Z here, but I was genuinely confused about how someone with distinctively liberal ideas (edit: liberal to the point of abuse) about the liturgy could be described as "excellent" when it is my understanding that those ideas are simply misguided and incorrect.

Also.... I am really, really tired of the contemporary non-understanding of logic and rhetoric that essentially casts any position you disagree with as illegitimate. You can disagree with someone, that is, actually think they are wrong in their conclusions, without dismissing them or their argument as if it is inherently illegitimate, invalid, and stupid. "Someone who disagrees with X cannot possibly be taken seriously" is a prime example of this sort of thing.
Stop it.

You didn't say the person in question is abusive, just that he is liberal. Those are not the same thing.

Yeah, I'm confused. I agree with Adam: one can be liberal (whatever that means) without being heterodox, abusive, or completely wrong. One can even disagree with the pope (although the body of scholarship done by the current pope should give one pause to do so...)

"if a liturgist advocates actual abuses of the liturgy and is then praised for being "excellent," what's the deal?"

I will say I wonder about this. I guess they're probably thinking along the lines of those who love maniples or silent canons in the OF liturgy. "It turns out better, or has a historical precedent, so who cares if it's not really called for?" It's shoddy reasoning, whether a liberal or a conservative is using it.

I guess people will like whom they like, especially if that person sides with their own ideology. For example, I know people who think The Marriage of Figaro is a great composition. But opera is terrible music, so clearly Figaro can't be even a decent composition!

Could you give me an example of something a "liberal" liturgist would do that is not heterodox or abusive?

The two obvious ones are probably:
Versus populum.
Option 4, alius cantus aptus.

And I can also think of:
-a giant bonfire at the Easter Vigil
-pouring a generous amount of oil on those being confirmed
-preferring a congregation be seated antiphonally rather than all facing one direction
-any architectural/artistic/haberdashery preferences other than High Baroque
-preferring the OF to the EF (without thinking the EF is evil or bad)

Thanks for your response, Adam. I think I understand you very well now, and I'm sorry if the terminology I originally chose led you to think that my position was different from what it really is.

What worldview acknowledges the "expertise" of those who oppose the directives of the church?

I'm not talking about things that specifically happen during the liturgy, which are, unfortunately, frequently out of the control of the Pontiff, but of the idea of what the liturgy should be.

I'm not sure why people always say that the Pope has no say in some of which occurs during his Mass. You could bet that if I were Pope (haha!) and I heard bongo drums and kazoos during Mass, you'd NEVER hear it again. Certain people would also probably be transferred to a diocese in Siberia...

Well, there are a lot of people with confused opinions and erroneous philosophies about the liturgy. There! That explains it! :-)