Don't be positive. Be critical and say this is wrong, this is broken, I would need to do this because of this. Anything to make the owner feel like they need to negotiate down on the price!
Don't be afraid to wait to put an offer in, build the suspense.
On the construction side look at the base of the house, does it look damp? When was the last time the boiler serviced? Is the corner of the building straight or bent as it could indicate problems with the subsidence? Try, open and shut windows, don't be afraid to look in wardrobes and cupboards, pull and push, turn taps on and off, flush toilets etc (hiding places for crap and cover up repairs).
Any damage to guttering, any cracks in the bricks etc?