I have a question regarding Google policies on the frequency of page updates. I have an automatically generated ad section on every page of my site and it's being updated every time the page is loaded. So every time Google bot comes to the page it gets different portion of text here. Ad section takes about 20-40% of the page. Can it be dangerous? Or Google allows some portion of content to be dynamically changing? I suppose many sites might have the same ad rotation...
Second question is regarding the dynamic updates of page title and meta-tags. I use a function to dynamically generate relevant description and keyword meta tags, but the lists are being generated in random order, so every time I update pages (and I do it every 1-4 weeks) these meta tags are being updated (almost all the words remain the same, but the order is being changed). Part of the title tag has also several relevant words (about 30% of title length) that get changed on updated. So the question is will these frequent changes of title and meta-tags do any harm to my sites position in Google?
My site had had a good position in SERPs, untill it started missing cache and description snippets on Google result pages a couple of months ago. May it be related to the above-mentioned frequent updates of the pages?
