  Over the past decades, nearly a million quasars have been explored to shed
light on the evolution of supermassive black holes and galaxies. The
ultraviolet-to-optical spectra of type-1 quasars particularly offer insights
into their black hole activities. Recent findings, however, raise questions
about the prevalence of red type-1 quasars of which colors might be due to
dust-obscuration and their potential influence on luminosity-related properties
of quasars. We examine the fraction of red type-1 quasars within the redshift
range of $0.68\leq z < 2.20$, applying spectral energy distribution (SED)
fitting using optical-to-MIR photometric data of Sloan Digital Sky Survey Data
Release 14 quasars. Approximately 10\,\% of the type-1 quasars exhibit red
colors suggestive of dust obscuration. There is an association between the
brightness of the MIR luminosity and a higher fraction of red type-1 quasars,
albeit with negligible redshift evolution. By employing $E(B-V)$ values from
the SED fitting, we obtained dereddened luminosity of the red type-1 quasars
and reassess the quasar luminosity function (QLF) and black hole mass ($M_{\rm
BH}$) estimates. Result shows a modest increase in the number density of bright
quasars, linking to more flatten bright-end slope of QLFs, while $M_{\rm BH}$
adjustments are minimal. Current SDSS selections in optical could miss a
significant population of heavily dust-obscured quasars. As future MIR surveys
like SPHEREx expand, they may reveal enough obscured quasars to prompt a more
profound revision of fundamental quasar properties.
