As a workaround, you may use csquote's \MakeAutoQuote macro to define active characters which may be used instead of \mkbibquote. (In my example, I use « and ».)
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[american]{babel}
\usepackage{csquotes}
\MakeAutoQuote{«}{»}
\usepackage[style=authoryear]{biblatex}
\usepackage{filecontents}
\begin{filecontents}{test.bib}
@article{ref,
sorttitle = {Handle Quotation Marks within Article Titles},
author = {Lastname, Firstname},
title = {Handle «Quotation Marks» within Article Titles},
journal = {Journalname},
volume = {10},
date = {1},
pages = {5--10}}
\end{filecontents}
\bibliography{test.bib}
\DeclareFieldFormat{sentencecase}{\MakeSentenceCase*{#1}}
\renewbibmacro{title}{%
\ifthenelse{\iffieldundef{title}\AND\iffieldundef{subtitle}}{}
{\ifthenelse{\ifentrytype{article}\OR\ifentrytype{inbook}%
\OR\ifentrytype{incollection}\OR\ifentrytype{inproceedings}}
{\printtext[title]{%
\printfield[sentencecase]{title}%
\setunit{\subtitlepunct}%
\printfield[sentencecase]{subtitle}}%
\newunit}%
{\printtext[title]{%
\printfield[titlecase]{title}%
\setunit{\subtitlepunct}%
\printfield[titlecase]{subtitle}}%
\newunit}}%
\printfield{titleaddon}}
\begin{document}
\textcite{ref}
\printbibliography
\end{document}
This problem is due to biblatex-apa's (apa.bbx's) apaauthor name format; you might want to notify the author of this small bug.
The string and others in the author list sets ifmorenames to true. apaauthor checks for this case whenever a name is printed, not just at the very end of the list; consequently it prints the andothers string ("et al.") after each name.
The fix is to add the following lines to your preamble.
\DeclareNameFormat{apaauthor}{%
\ifthenelse{\value{listcount}=\maxprtauth\AND\value{listcount}<\value{listtotal}}
{\addcomma\addspace\ldots\addspace}
{\ifthenelse{\value{listcount}>\maxprtauth\AND\value{listcount}<\value{listtotal}}
{}
{\ifthenelse{\iffieldequalstr{doubtfulauthor}{true}}
{\mkbibbrackets{\usebibmacro{name:apa:last-first}{#1}{#3}{#4}{#5}{#7}?}}
{\usebibmacro{name:apa:last-first}{#1}{#3}{#4}{#5}{#7}}}}%
\ifthenelse{\value{listcount}=\value{listtotal}}% this test is new
{\ifmorenames{\andothersdelim\bibstring{andothers}}{}}{}}
The MWE
\RequirePackage{filecontents}
\begin{filecontents*}{\jobname.bib}
@Article{boker2011,
Author = {Boker, S. and Neale, M. and Maes, H. and Wilde, M. and
Spiegel, M. and Brick, T. and Spies, J. and Estabrook,
R. and Kenny, S. and Bates, T. and others},
Title = {Open{M}x: {A}n open source extended structural
equation modeling framework},
Journal = {Psychometrika},
Volume = {76},
Number = {2},
Pages = {306--317},
year = 2011
}
\documentclass{apa6}
\usepackage[american]{babel}
\usepackage{csquotes}
\usepackage[style=apa,maxnames=999,sortcites=true,sorting=nyt,apabackref=true,backend=biber]{biblatex}
\DeclareLanguageMapping{american}{american-apa}
\addbibresource{\jobname.bib}
\addbibresource{biblatex-examples.bib}
\DeclareNameFormat{apaauthor}{%
\ifthenelse{\value{listcount}=\maxprtauth\AND\value{listcount}<\value{listtotal}}
{\addcomma\addspace\ldots\addspace}
{\ifthenelse{\value{listcount}>\maxprtauth\AND\value{listcount}<\value{listtotal}}
{}
{\ifthenelse{\iffieldequalstr{doubtfulauthor}{true}}
{\mkbibbrackets{\usebibmacro{name:apa:last-first}{#1}{#3}{#4}{#5}{#7}?}}
{\usebibmacro{name:apa:last-first}{#1}{#3}{#4}{#5}{#7}}}}%
\ifthenelse{\value{listcount}=\value{listtotal}}
{\ifmorenames{\andothersdelim\bibstring{andothers}}{}}{}}
\shorttitle{IFA}
\begin{document}
OpenMx \parencite{boker2011,aksin,wilde,murray}
\printbibliography
\end{document}
then yields
Update 2013-10: This has been corrected in biblatex-apa version 6.4 according to a comment below the question from user PLK.
Best Answer
Indeed. From there to the "inconsistent" in the title, it is a step though... I haven't done the setup, but to me it seems that it is different for each entry type precisely to be consistent with how the title is formatted elsewhere (bibliography, etc.).
But, as usual, with
biblatexyou can have it your way. The starred version of\DeclareFieldFormat*allows you to override all type-specific settings for a particular format: