Are you linking your affiliate or CPA links directly as the destination landing page for the ads? If yes then that might be the reason why Facebook are not approving your ads.

Some people say they can get cheap clicks on Facebook Ads, I never figured out how to get lower than fifty cents a click. I've been having some luck ranking Facebook pages on Google, and it doesn't require approval. You can redirect them to any URL from a tab using Just Redirect.

FB staffs hate their jobs, so they keep disapproving ads

Here's how I do, to get approved lots of my ads...

1) I do not create 1-3 ads and wait 6 hours to get approve
2) I create 100+ ads and submit all of it on the same time
3) 10-30% of my ads get approve
4) For the disapproved ads, I keep re-submit it again.
5) Keep re-submit the disapproved ads, until it approved
6) If some ads have been disapproved for 5-6 times, make a changes.

With this way, I get 80-90% of my ads approved. Although it's need times...

Advertise a Fan page instead of your site, then you might be able to redirect your fans wherever you want on your fan page.

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Facebook loves it when you link your audience back to your fanpage. For my campaign I have done so and all the ads are approved within 30 minutes time. Talk about efficiency.

Promote fanpages, Your ads will be approved fast & you will get cheap links.

What 'general' reasoning are Facebook giving for rejecting the ads?

Is it the least helpful one of just apparently not accurately representing the page or product you are promoting? Facebook kept rejecting my ads on those grounds - it turned out they just took a real dislike to the image I had on there - which was just a guy giving a thumbs up.

If you can share a screenshot of a couple of the ads that have been rejected and the URL you have been trying to direct to it would help give more specific advice on what's going wrong.