One of the audio greats, Jonas Miller, who ran the ultra high end Jonas Miller Stereo in Beverley Hills, told me to NEVER use denatured alcohol, because there are many ways to denature alcohol.
He pointed out that there is only one way to make high purity ethyl alcohol, or failing that, premium high proof vodka. Either of these costs almost nothing in the quantities used for cleaning.
More important is the problem of contamination. ALWAYS pour out a tiny quantity and throw away the excess. NEVER dip a cleaning tool into the bottle of alcohol.