I'm having the exact same issue and it is definitely new to the Raspberry Pi B+. I have an LG 32LS3450-UA TV to which I hook my Raspberry Pis. I have three original Model B RasPis and they all work perfectly out of the box with any cable in any position and any power supply I have.
On Tuesday, I received a B+. It sort of worked with my TV, but it flickers and glitched a lot out of the box. After a while HDMI just stopped showing anything at all. I tried two different cables and three different power supplies with no luck. Jiggling the cable into certain positions would sometimes make it work, but it was extremely unreliable. I then enabled HDMI safe mode, and found that it worked at low resolutions. Upping the resolution to 800x600 (HDMI group 2, mode 9) still worked, but showed some graphical corruption sometimes and sometimes went out. Upping the HDMI boost level to 6 (from 4) and jiggling the cable more fixed that. At 1024x768 (group 2, mode 16), it also sort-of worked with boost level 6, but the screen occasionally flickered when in GUI mode (x server running).
I tested both my cables and all three of my power supplies with my three older Model Bs, and they all still worked perfectly at full resolution with my TV. I then concluded that I had a defective B+, so I got a replacement today that came under warranty. Same issue happened again!!! Jiggling the cable into a particular position can make it work, but it's unreliable and flickers if the cable shifts even slightly. I'm using high quality cables and good power supplies (iPad chargers).
There is definitely some hardware difference between the B and B+ that causes HDMI issues with LG TVs. The same hardware is rock solid with the model B but nearly unusable with the B+. I don't have any other TVs to test with for now.