String cites are almost universally condemned. 
Judges at all levels criticize string cites. Minority and dissenting judges criticize majorities that use string cites, and vice versa but to a lesser extent. Attorneys criticize the string cites in their opponents’ briefs. Law reviews insult string cites routinely.
What distinguishes a string cite from a list of cases that support the stated proposition?
Its great length; some string cites are two or more pages long. E.g., Pelfresne v. Stephens, 35 F. Supp. 2d 1064, 1076 n.10 (N.D. Ill. 1999) (“The court does not appreciate Kusper and Peppers’ use of a gratuitous four-page string cite to support the simple proposition that conclusory allegations of a conspiracy are not sufficient to state a claim under § 1962(d).”).
Its high volume of cited pages; a string cite to testimony or administrative materials may cite to several hundred pages and multiple witnesses in the record. E.g., Sierra Club v. City of Orange, 163 Cal. App. 4th 523, 536 (2008) (“plaintiff employs a string-cite response, referring to numerous pages of the administrative record with little or no explanation of how each citation supports the assertion”).
Its lack of explanatory material about the cited cases. E.g., In re Flash Memory Antitrust Litigation, 643 F. Supp. 2d 1133, 1063 (N.D. Cal. 2009) (“lack of individualized analysis by the parties is unhelpful”).
Its inclusion of decisions from other jurisdictions without explanation for their application. Williams v. Glash, 789 S.W.2d 261, 265 n.3, 266 n.1 (Tex. 1990).
Its inclusion of citations that are ambiguous or so generalized in content as to be inapplicable. E.g., Matter of Peter J. Schmitt Co., 154 B.R. 632, 635-36 (Bankr. D. Del. 1993) (“If the legal proposition is not controversial, there is no need to cite more than one case, preferably from the [relevant] Circuit. If the proposition is controversial, or there is a ‘split’ in the decisional caselaw, mere citation to a number of cases supporting the advocate’s view by itself is not beneficial. The court does not analyze legal issues by counting the number of decisions in favor or opposed to a result. What is beneficial is for the advocate to choose the most well-reasoned case or cases supporting its position, and to carefully review that reasoning. In those rare circumstances where it is also appropriate to indicate the overall “’headcount’ on an issue of law, the preferable method is to cite a secondary source that has already collected the cases on both sides.”).
Its use to support propositions for which there is little or no dispute. E.g., United States v. Christie, 570 F. Supp. 2d 657, 681 (D.N.J. 2008), aff’d, 624 F.3d 558 (3d Cir. 2010), cert. denied, 131 S.Ct. 1513, 179 L. Ed. 2d 335 (2011).
Citations in the string cite may well be wasted as courts recognize their discretion to elect to disregard the string citations entirely. In McKevitt v. Pallasch, 339 F.3d 530, 533 (7th Cir. 2003), the court noted that Illinois had a statutory version of the reporter’s privilege that probably did not apply for several reasons. These reasons did not need to be considered because, “[i]n any event, while the reporters’ motion included a citation to the Illinois statute as part of a string cite, it failed to discuss, even minimally, why the statute should apply here. As a result, even if the statute were applicable, the reporters waived reliance on it.”
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