Excess grease means they were greased well. Pivots don't leak as such - whenever you grease them it pushes grease out the pivot. Those don't look like old grease so much though - they look like new grease. Perhaps he just greased it before selling it? It's always hard to tell, and I usually figure that most people are basically decent, so I'd focus on assessing the seller a bit. There are a lot of things people can cover up if they're dishonest, and any walk around you do won't see them. But if someone seems basically decent, and the walk around and test run seem good, then honestly it's hard to break a Kubota with 200 hours on it.
I bought a BX2350 (the bad plastic model) that had been heavily abused. Used by a commercial company, they clearly let the apprentice drive it. Every panel on it broken, the bits that said "don't step here" clearly stepped on. It was ugly, and the auction house weren't clear if it even ran. Bought it for a bargain, it started first time, and ran perfectly for 3 years before I upgraded. Kubotas are pretty tough, you'd be very unlucky for a 200 hour machine that's only 6 or so years old to have something major wrong with it.
