couple neighbors have offered their 1-2 year old pressure washers

what are some things to look out for in terms on maintenance performed, neglected,
check out, etc.. before I buy one ?

for example, if machine is a 3800psi, 4gpm system and it has been used just a few
times (less than 5) in one year, should the oil have been changed twice in that
timespan? would system have corroded if it just sat in garage unused for 6-8 months?
would the seals leak or something else that I'm not asking?