Bob's (robertsunrus) evaluation is spot on in my expirience.
I use to be a service manager and my department sold 'Service Contracts' (SC), we weren't allowed to call them Extended Warranties due to liability from that.
Doing the spreadsheets tracking it, I found that 10% of SC buyers used 90% of the monies we took in. That left around 10% profit. Not bad for doing nothing except making a phone call and selling the SC.
The economy caused us to look very carefully at the contract when we needed to get that profit up, and we didn't care much when the economy was good so the customers seldom had to complain. But we still denied some claims for things not covered or abuse, as spec'ed in the contract.
Since I worked in the industry and was familiar, I checked on SCs for RVs when I started RVing and found that the same thing pretty much happens there with SCs. When the economy is bad, they will fight you tooth and nail. When it's good, they'll pretty much deal fairly with you 10%'ers as we called you in the industry. But...it's the fine print that'll kill you even then.
And no, I've never bought one for my RVs.