Two things to look for on that used boat is how the boat sits on the trailer, what iam talking about is that the bunk boards or rollers support the stern of the boat. Boats that live their life on trailers, that. Were never properly adjusted
To match the size of the boat .Can have what is called a CUP, in the stern , dents in the back of the bottom of the boat from lack of support, all the weight in the back of the boat bouncing down the road has to have the bunk boards
Come right to the edge of the transom, to support the eng.
Weight.
If the bottom of the boat has cups in it, it will be very hard
To control at low speed, and they act like trim tabs, keeping the bow down, hard to get up on plane.
#2 check the stern over REEL close for any cracks or holes not filled with sealer, try to wiggle the outboard up and down, transom ROT, is a big problem, older boats have had a lot of transducers mounted and screwed into
Them, allowing water to keep the wood soaked.
Check the steering, the steering wheel should turn easy
Changing the steering cable, requires pulling the outboard off the boat, most owners don't have the means to do that.
I'll add a couple more things, if the dealer or owner will let you try to tighten the engine mounting bolts, they should be tight, if you can turn them / tighten them the transom has rotten wood inside.
And best of all is to have a compression test done on the engine, all the cylinders should be with in 10% of each other