Non-bitmapped "thumb up" symbol for flagging "good practice" tips

A free SVG version can be found on Wikimedia: Symbol thumbs up. The file Symbols_thumbs_up.svg can be converted with Inkscape to PDF like in this answer:

inkscape --export-pdf=Symbol_thumbs_up.pdf Symbol_thumbs_up.svg

The white margins can be removed by pdfcrop:

pdfcrop Symbol_thumbs_up.pdf

The result is Symbols_thumbs_up-crop.pdf.

In LaTeX it can be included, mirrored and resized by package graphicx with a driver that supports PDF. Otherwise it can be converted to EPS via pdftops of xpdf or poppler:

pdftops -eps Symbols_thumbs_up-crop.pdf Symbols_thumbs_up.eps

LaTeX example that defines \LeftThumbsUp and \RightThumbsUp:

\documentclass{article}
\usepackage{graphicx}

\newcommand*{\RightThumbsUpAux}[1]{%
  \begingroup
    \sbox0{Ag}%
    \raisebox{-\dp0}{%
      \includegraphics[{%
        height=\dimexpr\dp0+\ht0\relax,
        #1%
      }]{Symbol_thumbs_up-crop.pdf}%
    }%
  \endgroup
}
\newcommand*{\RightThumbsUp}{%
  \RightThumbsUpAux{}%
}
\newcommand*{\RightThumbsDown}{%
  \RightThumbsUpAux{origin=c,angle=180}%
}
\newcommand*{\LeftThumbsUp}{%
  \scalebox{-1}[1]{\RightThumbsUp}%
}
\newcommand*{\LeftThumbsDown}{%
  \scalebox{-1}[1]{\RightThumbsDown}%
}

\begin{document}
\begin{tabular}{ll}
  \LeftThumbsUp    & \verb|\LeftThumbsUp|\\
  \RightThumbsUp   & \verb|\RightThumbsUp|\\
  \LeftThumbsDown  & \verb|\LeftThumbsDown|\\
  \RightThumbsDown & \verb|\RightThumbsDown|
\end{tabular}
\end{document}

The fontawesome package is a good go-to for things like this:

\documentclass{article}

\usepackage{fontawesome}

\begin{document}\Huge

\faThumbsDown

\faThumbsODown

\faThumbsOUp

\faThumbsUp

\end{document}

It does not appear to pixelate even at 400% zoom level in my PDF viewer:

Create a new character.

\documentclass{article}

\usepackage[]{graphicx}
\usepackage{scalerel}
\def\thumbsup{\scalerel*{\includegraphics{up.png}}{O}}
\def\thumbsdown{\scalerel*{\includegraphics{down.png}}{g}}

\begin{document}
thumbs up \thumbsup

thumbs down \thumbsdown
\end{document}

0 and g refers to the character used as reference of size and vertical position. For those I tested, the best combination is as it is. Figures up.png and down.png must be attached to your folder.

Of course, if you prefer another thumbsup/down picture, you can change it.