Just like you have a choice when choosing a Realtor to work with, you have a choice when choosing a home inspector/company. And just like with any profession, there's the good, the bad and the ugly... That might be a bit extreme (all the Inspectors I've met here have been pretty easy on the eyes) but sometimes their reports are not. And finding someone you know you can trust and who will do an excellent job is important on both sides of the transaction - for the buyers AND the sellers!
There are the major issues to look out for (Electrical, Plumbing, Roof Covering and Structure, Foundation and HVAC) and then other minor things like maybe a loose toilet bowl (I see that all the time, not sure what is says about us as a society).
It is crucial though, that you find an inspector who will have a detailed report but also be able to tell you what is actually a big deal and what is a $20, 10-minute fix.
And most good inspectors will do a pre-listing inspection for sellers, which can be beneficial for buyers too. First impressions are everything, as they say, and that goes for homes. IF things look bad at first glance, it often indicates that there are more problems to come. If a seller can get ahead on some repairs they can possibly get better and more offers!
If you aren't sure, ask your Realtor - they should recommend more than one, but they will have come across likely the best and the worst from all sides so ask who they would use on their own home!