bloupbloup - 11:52 am on Jul 24, 2012 (gmt 0)
I would like to say that i hate both 404 and 410. I tried them both and i did not see the difference. Nevertheless, i only saw that 404 and 410 harmed by Internet Traffic.
I dont know lots of things but i am sure about it.
After deleting pages, i looked in my logs. I have seen that googlebot was slow to get rid of the 404 errors. For instance, if you remove 100 pages. You are going to get 100 404 errors in your logs. After each log, i have witnessed the same behaviour from googlebot, It disappears for sometimes. It is like 404 or 410 errors slowed down crawling. Interestingly enough, The Traffic also goes down and then recover zhen there is no 404 errors anymore. In webmaster tools, 404 appears as "crawling errors". It can take up to 6 months or even one year to flush 404 errors if you have few backlinks.
Google says that 404 is OK but i dont see that in the logs