"You'll be much better off buying an ex-racer when looking at off road bikes."
+1
Unless it was ridden by 1 of a handful of really fast guys the bike was trail ridden. However, whether it was a fast enduro guy or not it was more than likely well maintained if he was racing and relying on it.
If it's 5 years old then it's a 2007 and bent forks or frames would be rare and very obvious. It's also likely a 4 stroke.
Befor going to see it check the web for owners groups. See what mods & fixes are advocated and make notes regarding what to ask about or look for. It is best if it's stock but that's pretty rare.
With the bike on a stand (both wheels off the ground) Here's what I would look for/at:
Check the condition of the wheels. Rim dents, loose or busted spokes. Rim dents happen and if it's a small one it's no big deal. Busted or loose spokes indicate laziness when it comes to maintenance. Check the brakes. Rotors should be in good shape with minimal scoring or discoloration. Pads need to be replaced frequently, particularily in sandy or muddy conditions. Check the brake fluid, it should be clear. If it's dark and not transparent (in the back) it's been boiled and is a sign of hard use. Not that hard use is bad but not changing the fluid is.
Check wheel & swingarm berrings for side play. Again, they do wear out, albeit slowly with average use but age quickly for a top level rider or crappy maintainer. You should check the steering head bearings too. 20 years ago they would wear out fairly quickly but not so much nowadays but it's worth checking. With the front wheel off the ground grab the bottom of both fork legs from the front and pull and tug strait ahead. There should be NO play whatsoever.
Chain & sprockets, not necessarily expensive to replace but should ALWAYS be kept in good shape. Sharp, broken or mis-shaped teeth are no good as is excessive side to side play in the chain.
Check suspension action. Both ends should move freely with no squeaks etc. Check for leaks at both ends. Also make sure the adjustment screws are OK. These are sometimes brass and a ham-fisted owner can screw them up. Out of curiousity unscrew the air bleeder screws on the forks to see if there is alot of air in them. Myself and the guys I rode with would maintain our bikes obsessively on a weekly or bi-weekly basis. there was NEVER a buildup of air in the forks, after the days of air assist mind you.
Check the crankcase for leaks. Drain a bit of oil, is it clean? Is it new? Do you still have the old stuff? If it's in a bucket check to see if there's debris on the bottom. Check the action of the gear shift. Positive and precise or loose and sloppy?
Check the air filter and air box. Clean or dirty? Is there dirt in the air box? If there is and the filter is in poor shape I would be somewhat concerned depending on price.
Make sure there are no oil leaks around the head or base gasket, also the valve cover, again for a 2007 there shouldn't be.
Check the coolant in the rad. It should be in good shape and at the proper level with no sign of contamination.
Find out what kind of aftermarket exhaust is on it. make sure it has a spark arrestor. Ask if he still has the original.
There's a good shop in Barrie (Mission Cycle I think) they might be helpful.
If it's a guy who's raced enduros and looked after the bike (most racers) then it will be fine and he won't mind you looking it over carefully. If he has any issues with close inspection....walk.
Good luck. Searching for a bike can be alot of fun too. I've met some REALLY good guys and learned alot from them over the years.