I disagree based on my personal experiences.
Torn boot = Many possible reasons. Most probable reason is wrong installation as it was recently done. A twist in the boot while installing clamps results in this as well. Any external damage like a stone or thread on the boot also results in a torn boot. Maybe there was already a crack on the boot.
Black Grease = Possibly correct grease. The CVJ grease mostly available in Pakistan in black/dark grey in color. Extremely messy and impossible to get off clothes.