Keyword and Title House-keeping

Hi there, thanks all for your time and effort in answering. 

I have some files that have never sold. There's nothing wrong with these files but I uploaded them when I was a lot less experienced and my titles were 'wordy' and I tried to fill as many of the keyword slots as possible (almost all most of the time) 

Now I've started culling the portfolio,. What I now look at and see as trash that no longer stands up I simply delete it. 
For the images that I will keep that as yet have no sales, is it worth while to give fresh titles and redo the keywords to ensure only 'truly' descriptive and useful words are included or are those images already doomed due to some mystical algorithym?