Here is a tikz implementation that underlays the "scary replication" using atbegshi, thus preserving the black overlaid text.

\documentclass{article}
\usepackage{tikz,atbegshi}
\usetikzlibrary{calc}
\newcounter{wordcount}
\newcommand{\scarymacro}[2][10]{%
\stepcounter{wordcount}%
\tikz[remember picture, baseline, inner sep = 0pt] \node[anchor = base] (scary\thewordcount) {#2};%
\begingroup\edef\x{\endgroup\noexpand\AtBeginShipout{\noexpand\AtBeginShipoutAddToBox{
\noexpand\begin{tikzpicture}[remember picture, overlay]
\noexpand\foreach \noexpand\x in {1,...,#1}{%
\noexpand\pgfmathparse{rand}\noexpand\edef\noexpand\xdir{\noexpand\pgfmathresult}% X-direction
\noexpand\pgfmathparse{rand}\noexpand\edef\noexpand\ydir{\noexpand\pgfmathresult}% Y-direction
\noexpand\pgfmathparse{100*(0.1+rnd*0.5)}\noexpand\edef\noexpand\scaryshade{\noexpand\pgfmathresult}% Shade
\noexpand\pgfmathparse{0.5+rnd*0.5}\noexpand\edef\noexpand\scaryscale{\noexpand\pgfmathresult}% Scale
\noexpand\node[color = red!\noexpand\scaryshade, scale = \noexpand\scaryscale]
at ($(scary\thewordcount)+\noexpand\xdir*(1cm,0)+\noexpand\ydir*(0,1cm)$) {#2};}
\noexpand\end{tikzpicture}
}}}\x%
}
\begin{document}
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Duis rhoncus cursus
mi in pretium. Duis faucibus, leo sit amet hendrerit tempor, urna risus elementum
leo, in tempus metus justo id nisl. Morbi adipiscing sapien venenatis est rutrum
\scarymacro{scary} egestas. Phasellus commodo odio diam. Aenean a euismod diam.
Maecenas lacinia tincidunt dolor nec posuere. Praesent accumsan consectetur luctus.
Maecenas ac lorem at elit egestas scelerisque. Quisque tristique ligula sed nulla
scelerisque, ut porta dolor faucibus. Sed et dui ac justo ultrices molestie. Sed
tempus vitae dolor in sodales. Cras molestie elementum turpis in pharetra. Nullam
turpis metus, iaculis nec \scarymacro[4]{scary} consectetur quis, adipiscing eleifend
massa. Quisque blandit nisl id nisl fringilla commodo. Phasellus non faucibus
tellus. Morbi non justo mauris.
\end{document}
...a close-up something scary:

The scary text is replicated 10 times by default when using \scarymacro{<stuff>}, but an optional argument can also be used to adjust the number of replications. Replication is printed in colour ranging from red!10 to red!60, scaled between 50% and 100%, and randomly placed within a 1cm x 1cm proximity of <stuff>.