cocktailqueen - sorry I missed your comment addressed to me 
I also know very little about dance, and am very biased towards Jay 
But - I think Kevin and Kelly were overmarked to keep them out of the dance off again - I thought their routine was horrible, I also thought Helen was overmarked - her head was flying about all over the places, ditto Peter whose feet were totally hidden by smoke and who has made no progress IMO from the first show. I thought Katie's rumba deserved a higher mark than Kellie's samba which looked quite stiff legged to me.
So in my conspiracy theory world I conclude they are not very popular - and judges are bumping them up the board to give them extra overall mark.
Some people always seem undermarked - Jay and Anita mainly - Jay show excellent technique but gets criticised for lack of performance skills - but his technical ability seems to count for very little (especially with Craig) - performance always seems to get marked above technique. Both elements should come into it.
I am guessing Jeremy and Jay (Jay having the higher vote) are popular with the public, therefore in order to get Jeremy in the dance off they put Jay just above him and assume Jay will get his usual number of votes and create a bigger gap between Jeremy and the rest of the board so that mathematically it is likely Jeremy will be int he DO.
It is entirely possible probable that this is nonsense and I have gone bonkers and become overinvested in a TV reality show 

Georgia is not my favourite but she dances well and I thought she (almost) deserved tens (she was out of synch in a couple of places - or maybe Joe Varney was !)