Starting from Aram. sheqar and shiqray/sheqarya, "liar," which with the ending -a and with aleph prostheticum becomes ishqarya, Iscariot can be taken as "the liar, the false one" ...I have a number of problems with this proposal. First of all, there is not, as far as I can tell, any Aramaic word shiqray, sheqarya that means "liar." The idea that there is apparently comes from an error in Jastrow's Dictionary (p. 1626, s.v. שׁקרא), where he misinterprets a verbal form in b.Yev. 55b שׁקרי , "I lied" — as an adjective. That is the only "attested" use of this otherwise non-existent word. The normal Aramaic word for "liar" would be shaqqar, which cannot be made to yield "Iscariot."
Secondly, you can't just tack on a prosthetic aleph any place you want to; it occurs primarily on words that begin with consonant clusters (which shiqray does not). As far as I can determine, prosthetic aleph is not attested with this root at all in Aramaic. So what we have here is an arbitrary syllable added to a word that does not exist; and this is proposed in a widely used lexical tool as the most probable etymology! (I. Howard Marshall, in his commentary on Luke, also refers to this as the "most plausible" etymology.)
The old idea that Iscariot means "man of (the town) Kerioth" (Hebrew ish qeriyot) is still the best. Limbeck objects that a Hebrew surname would not be used, but I think this is not true; tombstones and ossuaries from the first century CE bear names in both Hebrew and Aramaic. Plus, names with ish + city name are quite common in the Mishnah. Here's a few:
Natai Ish Tekoa (Hal. 4:10)
Yosi ben Yoezer Ish Zereda
Yosi ben Yohanan Ish Yerushalaim (Sota 9:9)
Yakim Ish Hadar (Eduy. 7:5)
Antigonus Ish Sokho (Avot. 1:3)
Halaphta Ish Kefar-hanania (Avot 3:6)
Levitas Ish Yabneh (Avot 4:4)
Eliezer Ben Yehudah Ish Bartota (Tev. Y. 3:4)
Judas's full designation in Hebrew would likely have been Yehudah ben Shimon Ish Qeriyot (cp. John 6:71, "Judas son of Simon Iscariot," which also has the variant reading "from Kariot" for "Iscariot").
BIBLIOGRAPHY: M. Limbeck, "Iscariotes," Exegetical Dictionary of the New Testament, edited by Horst Balz, Gerhard Schneider, p. 201.