In some cases, with amsmath, it seems that the dots are not well aligned. For instance, when in parenthesis, it is normally aligned, but when followed by a colon, it is in the middle of the line.
MWE:
\documentclass{article}
\usepackage{amsmath}
\begin{document}
$(\dots) = \dots:$
\end{document}
Which gives the following result:

\dotsit chooses between\ldotsand\cdotsdepending on the context, – David Carlisle Sep 05 '16 at 09:29