Is pluto conjuction pluto bad in synastry?
Definitely not. Squares and opposites on the other hand can be bad. I personally like to think of Pluto as the “drive” of a generation, how we handle our pain and how it makes us progress, our transformation, how we get affected by things that are more serious and out of our control.
Pluto-Pluto conjunction can show similar growth between two people, similar transformation throughout life, but it doesn’t really show depth to a relationship unless it aspects other planets. You have this aspect with pretty much everyone born around your year, since Pluto changes signs every 12-31 years.
Pluto-Pluto squares or opposites can be bad and definitely show the major differences between generations - refusal to change or accept the other, handling things differently, conflict of values and beliefs, etc.