New denim does tend to bleed a bit onto fabrics it’s in contact with, but i’ve never really had any issues with this because my blazer choices have always been navy or darker. After a few weeks of wear denim traditionally will lose most of it’s “bleeding” and it’ll be less of an issue. It has gotten me a few times on the elbow’s & waistlines of white shirts - but i don’t worry too much about it as it comes off with regular shirt washing.
fading will rid the denim of that ‘crisp’ look (it’ll take about 3 months) - I’ve recently found myself cycling through two pairs of dark indigo denim depending on the occasion. one i intend on maintaining it’s stiffness for as long as possible - the other i wear 4 days a week.
i know denim is an investment, but all the information i have from it is simply by trial and error.