Well I can see some HD twins fans saying (by the way, I own the 3 systems, Wii/360&Ps3), that the wii remote waggle is not proper gameplay and of course the graphics are horrible, even first party Zelda or Super Mario Galaxy games. But that is fan boy talk.

I do think there is a lot of junk in the 360 library, and since is an HD console, the design work may be easier for the developers. (I mean I think it can be hard to make a game look good with the Wii specs limitations). But I am looking for the main most blatant offenders. Because I think that most gamers, maybe not very young gamers, but seasoned gamers will always prefer gameplay over graphics.

Ah! I got one: What about Gran Turismo 5?

A lot of people think that Forza series (2, 3, 4 and horizon) is much better.
Agree?

true, but getting to "horrible gameplay" from that statement is a bit of a stretch.  I'm with Gergory on this one, a game that has had the effort put into it to look beautiful is always going to be debatably good from a gameplay point as well.  Closest thing I can think of to what you want are the "artsy" games like Flower or Journey, but I would disagree with the idea that they had "horrible" gameplay so it's just proof that these types of games are not going to be universally thought of as having bad gameplay.  

*insert Resident Evil game of choice here*

Forza may be better but I dont think Gran Turismo is bad either.  

I hear Lair would probably fit this description well.

El Shaddai
Final Fantasy XIV
Lair
Resident Evil 6

All pretty terrible games that are pretty.

CS:GO

Classic example: Final Fantasy VIII.

Ok, what about Heavy Rain?