Why did Snape teach Occlumency?/Snapes Trustworthiness

[sonjaaiston]

No: HPFGUIDX 103544

Why did Snape teach Harry Occlumency in OofP?

This is something that has been bothering me.  I usually don't post 
b/c I'm afraid the topic I want to discuss has been discussed ad 
nauseam.  I hope this already hasn't been completely hashed out:

My understanding is: Dumbledore didn't want to teach Harry 
Occlumency b/c he didn't want LV to see how close he was to Harry. 
So he had to find someone else.  Snape was excellent, so he was 
chosen to teach Harry.  BUT, my problem is, isn't it just as 
dangerous for LV to see Snape close to Harry?  Wouldn't LV put 
pressure on Snape to intefere with Harry.  Wouldn't LV question 
Snape's loyalty if he saw Snape helping Harry?  Is it possible that 
Harry did not succeed with Occlumency b/c Snape didn't want LV to 
see Harry succeed?  Maybe this was just a way for Snape to show 
his "loyalty" to LV so he could continue his "double agent" work. 
(Though, if that is the case, it is trully shameful that Harry was 
not warned about the prophecy and LV intentions.)

Snape's Trustworthiness:

Aside from the above topic, I'm am beginning to think Snape will end 
up being a traitor to Dumbledore ---- only b/c we have been told so 
many times (by Hermione and Dumbledore) that he is on Dumbledore's 
side.  Harry and Ron have suspected Snape many times only to find 
out they were wrong.  It seems JKR might be giving us a "false sense 
of security." 

Any thoughts?
Sonja