Milagro

Mulder:  If he imagines it, it's a priori-- before the fact.  I think that's pretty clear from what he wrote about you. [Scully stares at him.] Mulder:  You know you're in here, don't you? Scully:  [uncomfortably] I read a chapter.  What does he say? Mulder:  [quietly] Well, let's just say it ends with you doing the naked pretzel with "the stranger" on a bed in an unfurnished fourth floor apartment.  [He pauses]  I'm assuming that's a priori, too? Scully:  [short laugh, not looking at him] I think you know me better than that, Mulder.

Oh Mulder knows damn well that that was a priori.  Not that it was any of his business anyway.  It's not like he's dating her or anything.  Damn nerve of that Punk!

General Punkesque Behavior

Here's an attractive sight.  (Not!)  Mulder answering the door with a toothbrush stuck in his mouth.  Lovely.

Okay, Mulder answers the door with the aforementioned toothbrush in his mouth.  Scully sits on the couch and Mulder joins her.  What did he do with the toothbrush and more importantly what happened to (and there's no way to be delicate about this) all the toothpaste and saliva that had to have formed while he was brushing.  He simply didn't have enough time to run to the bathroom, spit and join Scully on that couch.

Making appointments for Scully without consulting her:  Did it even occur to him to ask to make sure the time was a good one?

Mulder has no right asking Scully if the scene in Padgett's book was a priori.  Mulder has no claim on Scully.  She's free to see anyone she wants and frankly her sex life (or lack thereof) is none of his business.  (Unless of course he has plans to change the current situation.)

Mulder is such an immature Punk!  When Scully asks about how he knew the body was in the truck Mulder's (sarcasm) enlightening (/sarcasm) answer is "I imagined it," a blatant throwback of an answer from a previous argument.

Unprofessional Behavior

Busting into Padgett's apartment without so much as a knock and looking through his stuff:  Uh, Mulder, did you have any plans of say, obtaining a warrant or do the idea of civil rights mean nothing to you?

Criminal Activity

Breaking into Padgett's mailbox:  As an FBI agent he's sure to know that what he did was a federal crime not to mention just plain unneighborly.