I guess that Google removes already indexed pages that are now returning the HTTP error 403. Unfortunately I can't find any definitive statement on that matter. Do you know the answer?
Some bots have been crawling my site for every link that ends with: ?utm_source=dlvr.it&utm_medium=twitter I haven't checked out its IP. Then other bots (10+) follow the link rules ?utm_source=...
EDIT: did more research, asked new question I dug a bit deeper and realized that the contents of the page are indeed not relevant to this issue. As this question has gotten more and more confusing, ...