I used 'Save a copy' in Illustrator to export *.ai as PDF files, only to find the color changed unexpectedly. Original color is
CMYK(0,0,0,95) but it has a red hue when viewed in Acrobat.
I have read this question: CMYK colours wrong on export in Illustrator. However, my Illustrator file is already in CMYK mode and I did choose not to convert the color in export settings (actually enforcing CMYK color in configuration made no difference).
Same problem exists when I open the PDF with Foxit Reader or Windows in-built reader.
I'm wondering, does the problem affect printing or only result from a screen glitch?
Thanks to @GoofyMonkey, I understood the problem was because Illustrator displayed the inaccurate color.
By the way, I am sort of curious about why 100K appears slightly red, instead of slightly blue or other color? Is that an intrinsic characteristic of CMYK or only some problems relating to showing CMYK colors on sRGB screen?