I have my a/c set to 74*F and I keep my rooms clean and I use an air purifier in each room to lower the dust buildup.
I have to PS3's, a CECHA01 60Gb, and a CECHE01 80Gb models.
They've never had any issues with overheating, and never had YLOD or ever had any repairs done.
60 GIG Ps3 Owner Since January 21, 2007
500GB Ps4 Owner Since November 22, 2014
1000 Model PSP Owner, PSP Go Owner and PS Vita Owner
PS1 and PS2, Both Original Systems.
I use a twistdock which sits my slim on a slightly raised vertical angle (http://www.vogels.com/press/press-release-archive/
* the first two links didn't come off as intended so search within the product page and you'll get there