The issue isn't your ISP or google.... it's Akismet (for spamming wordpress blogs anyway).... eventually all the ips in your dynamic ip pool will be blacklisted by Akismet and all your comments will be ghosted.
Actually Akismet is not an issue at all, IMHO. The reason being is, that akismet can ban you with as little as 3-5 comments reported, and I have placed legitimate manual comments before and got banned by akismet for it.
If you are posting at least 100 links per week, you WILL get banned by akismet, plain and simple. All of your proxy IPs will almost always be akismet banned, but you have to consider akismet is installed on less then 25% of all blogs (If I recall that figure correctly) so your after what you can get and with wordpress alone being MASSIVE, 10%+ of all new sites that come online daily are wordpress. So there is more fish in the sea to harvest then you could possible even keep up with, so akismet is a non issue.
Plus you have to figure, akismet is on more moderated blogs then is auto approve. Assuming your mass spamming, you will fall thru moderation sometimes, I have seen it happen on mine, but your probably largely after auto approve if your posting. If a owner of an auto approve blog thought spam was such an issue to turn on akismet, then they wouldn't have turned on auto approve. Auto approve is turned on, probably a lot of times by the people who either have no idea, or who are just not wanting to hassle with it, which is not the type of people that are going to take the effort to use akismet.
So mass spam is going after low hanging fruit, moderators that can't tell spam from non spam, comments that fall on the right post at the right time or auto approve. If your going after quality moderated blogs, then your going to first be filtering the list a lot and then probably manually commenting on the best ones.
My 2 cents.
I can't do just that! Anyone else has the same issue? The Build-in Proxy harvester module always giving a timeout error! I'm so frustrated...
It works fine for me. If its timing out its likely that you either have the connections turned up higher then your bandwidth can handle, so try turning the connections way down, perhaps to 1 or 5. OR its being blocked by security software, in which case you need to set scrapebox as trusted/allowed in all security software. Note that disabling security software does nothing, it only stops new rules from being created. You have to actually delete existing rules and then set scrapebox as trusted/allowed, else those old existing rules will still fire even when software is disabled.