First I'm going to say that these are not bugs caused by memory caching problems. The game and DLC's have been uninstalled and reinstalled. My 360 is NOT modded. These are legitimate BUGS within the game's programming.

After completing a good portion of DG (omw to meet Serana and travel to the Soul Cairn), and completing two vampire radiant quests, I took a moment to go back and do some other things in Skyrim (this being a new character I was working on). I go to Markarth and upon entering the first time, I kill Weylin to stop him from killing the imperial lady for the forsworn and it starts the vampire radiant quest "Distracting the Herd". I got a quest marker telling me to "plant the letter on the body" with no quest description beyond that. I wasn't wearing Dawnguard gear. I hadn't talked to anyone at the castle and received this quest. It was triggered upon killing Weylin. And yes, it failed the quest when I left the area. As someone who generally doesn't accept failed quests, this annoyed me.

No one notices when I'm a blood-starved vampire. I can freely walk around towns. And none of the invisibilities work, which I first discovered when I used Embrace of Shadows and only the Night Vision functioned. I suppose I should be thankful for the former bug because of the latter, lol.

There are times when I will be out in the middle of nowhere, turn into a Vampire Lord, receive a bounty because some Dawnguards have spawned nearby and the bounty doesn't disappear after I kill all of them.

There are plenty of times when I turn into a Vampire Lord and I will spawn in "magic attack mode" without any spells in my hands and I have to go back and forth several times between melee and magic mode before I can cast anything.

I don't like the absence of developer statements as to what they're planning on doing about these game breakers that they've created. I've always been of the opinion that if you say you're going to deliver on a product, you should follow through and do it, and if you did it the wrong way, then you should fix it before the people who've given you money for the product you said you would have for them start getting upset and possibly decide that as much fun as Bethesda games CAN be, perhaps they're just more trouble than they're really worth. I understand that they are busy, but their future products won't fare much better if people are under the impression that the developers don't care about they're product. Silence is equated to being ignored. No statement from Bethesda means that, whether or not it's their intent, they are giving the impression that they are ignoring their consumers. And no company worth its salt ignores their loyal supporters.

That's my opinion. If anyone else has any further bugs and / or comments on this, please feel free to state your mind.