Curious . . .
You lament sometimes not knowing Spanish or Arabic as well as you would like (or perhaps it was the assumptions that others have that you study Arabic?). What languages do you know as "well" as you would like?
None, I guess. I think there's always room for improvement. My Spanish is fine, I just lament having essentially lost that connection with the death my aunt and grandmother over the last decade and a half or so (now I'm the only Spanish-speaker in my family, so unless I marry into a Spanish-speaking family, it probably dies with me). I still use it around friends back home and whatnot, but I'm very rarely in a situation where I absolutely have to use it, since most people here in ABQ (and back home in CA) are bilingual, and those who aren't generally don't like it. There's a certain stigma using it in a mixed community, like you're choosing sides or something.
A question relevant to this thread, given your obvious expertise in language in general and I imagine better insight into methods of language acquisition than any of us have, what gets in the way of better your Spanish? Lack of time? Opportunity?
Time is a big one too, yeah. I've actually tried to schedule days to only use it (or only use Russian; I don't think I know enough Arabic anymore to use only Arabic for a whole day, though I used to converse with certain people only or primarily in Arabic back when I lived in Oregon and was using the language every day), as ridiculous as that sounds, but it never really works out that way.
If you don't mind saying, is there is a particular language you are expert or becoming expert in? If these are dumb questions, which they could be since I don't really know many linguists, or don't want to answer for whatever reason, no offense.
No, I wouldn't say so. As I have become more specialized in my training, I find myself regularly coming back to Afroasiatic languages (modern and ancient, particularly the more peripheral varieties), but this is something other than knowing any of them particularly well. That's not always, or maybe even not often, strictly necessary. That might sound odd, but for example, I have in the past done work on the loss of the emphatic set (T, D, TH ~ Z, S) in peripheral varieties of Arabic as spoken in Chad, Sudan, Cyprus, Afghanistan, Nigeria, Uganda, etc. To do that, of course you need to know enough about Arabic phonology in order to tell a probable story about which variety lost what, when, and why. But other than being able to work with text samples (when available), you could theoretically do this work without knowing any
Arabic. And I've worked with many languages in that situation.
There are, of course, many linguists who are experts in particular languages or language families, or aspects of the same. My old adviser at the University of Oregon is something of an expert on the Cariban family of languages (northern South America). But there are also a great number of linguists who are specialists in a particular subfield, rather than a particular language or family (and of course, the line between the two is fuzzy; someone like Niloofar Haeri, an Iranian linguist at Johns Hopkins who has worked a lot on sociolinguistics of Arabic, particularly Egyptian, is probably also at least conversant in the language due to her preexisting research interests in this variety in particular and the time she has spent in the field collecting data).