About the Downlite adware
If you are having a lot of advertisements injected into Safari, especially Dynamic Pricer ads, then you may be infected with the Downlite (aka VSearch) adware. This adware is also known to interfere with your ability to load content from sites like thesafemac.com or adwaremedic.com, in an attempt to prevent you from removing the adware.
If you believe that you are infected with Downlite, there are multiple possible solutions:
• Follow the manual Downlite removal instructions in The Safe Mac's Adware Removal Guide
• Use Apple's removal instructions: Remove unwanted adware that displays pop-up ads and graphics on your Mac - Apple Support
• Restart your computer in safe mode or disable JavaScript (in the Security pane of Safari's preferences), and then download AdwareMedic to remove the adware
Apple has recently decided to call some variants of Downlite malicious - perhaps because of behaviors like that described here - by adding a Downlite signature to the built-in anti-malware protection in recent versions of Mac OS X (XProtect). They have also revoked the developer certificate used to sign some malicious Downlite installers, meaning that the installer will no longer be allowed to open even if XProtect updates have been disabled. However, other Downlite variants are still active and not blocked by the OS.
(Fair disclosure: I may receive compensation from links to The Safe Mac and AdwareMedic, in the form of buttons allowing for donations. Donations are not required to use my site or software.)