If there's a significant and highly probable upside with an acceptable level of risk, then go ahead...  

When you look back at this deal in 10 or 20 years which will you regret more, walking away over wishy washy nit picky miniscule amount of money or will you regret accepting the sellers wishy washy nit picky terms and buying the 20% COC property?

If you waive your radon inspection and try to negotiate on radon, do so only if you are willing to accept the consequences. 

If they say that's acceptable, then dig a bit deeper.

Hey Jason,Thanks for this post, I am quite a newbie and just got a offer accepted on my 1st investment property.

Our main one was Northwest Trustee services  but I think they rebranded and are not under that name anymore.if the seller is not losing the property then there really is no reason to not go through title and as John states many scammers or those that sell bad title properties will try to get you to just accept a quit claim deed  etc.. 

I made an offer on a 4plex but they didnt accept my offer.

Only crazy sellers who are desperate will accept 203k loans and the like because of the headache they are.

If your investment can't absorb these inefficiencies and generate acceptable returns, you should consider syndications, lending funds or numerous other options for investing in Real Estate.

Don't get emotionally attached to a house and make plenty of offers that may not get accepted.