Odo wanted to bust up Rom's union for no other reason than public gatherings are disorderly. He wanted to arrest a group of pagh wraith followers who were peacefully chanting just because their presence annoyed his girlfriend. He speaks of the totalitarian occupation of Bajor as the good old days when things were safe and he wasn't bound by Federation rules. We see him monitoring Quark's private conversations and he claims he does so "routinely." Heck, he's thrown Quark into holding cells without evidence before and I've never seen him offer anyone legal counsel.
I like Odo, but he does have a huge fascist streak in him.