To buy or not to buy
 

Last year I sold my R1150GS as I was concerned with how much money I had tied up in it, and was scared of dropping it in the gravel and causing thousands of pounds worth of damage. I have had a year without wheels and can take it no more. I have found a pretty cheap £2000 2003 XT600 (though it does have a big dent in the tank which is apparently unaccounted for - ie the previous owner did it).
Is there anything I should look out for when viewing the bike (to give signs of abuse etc).