I have recently started with PPC for CPA, wanted to know, does direct linking PPC with CPA offer landing page get good Quality Score and conversion rates, or your own pre-sell landing page is a better performer or/and a necessity for a good QS.
Whether or not you will get a good quality score will depend on the actual landing page. Bigger concern is that you will not be able to use direct linking if any other affiliates or the actual advertiser is using it as well. When you are spending money with PPC it makes more sense to create your own page that not only sends traffic to whatever offer you want to promote BUT more importantly lets you build your own list. That way you can market to potential customers again and again.
Yes I was just coming to say basically what Merigot said. Google only allows one ad per domain, so if the advertiser or other affiliates are bidding only one will show - the one with the highest bid and/or quality score. Here's info about how that works. http://adwords.google.com/support/aw/bin/answer.py?hl=en&answer=14844
search for Amish Shah on Youtube.com. He explains some good points about getting a good quality score