You already mentioned a few things a lot of sponsors get wrong. For some reason a lot don't seem to realize that there is no way they can do any styling in advance that won't break the layout of someone's blog. The best thing sponsors can provide is just good text and large (but not too large) photos, with the links in the post pointed to wherever the affiliate selects in the sponsor's promo tools admin. Choice could be linked to gallery with pics, or mpg, or wmv, or update page, tour page, join page, etc.
If a sponsor can't offer choices for where the affiliate wants to send a surfer who clicks the photo or text link in rss feed post, then I agree with TPat that it's usually better to send the surfer to a hosted gallery instead of directly to a tour page. We've tested linking direct to tour and updates pages and so far those don't seem to convert as well.
I prefer sponsors to use larger photos in place of the small thumbnails some are using now. Or at least give webmasters a choice of photo sizes. I really don't like using tiny photos on blogs. Thumbnails are for galleries and TGP pages. Blogs need photos that are much larger. I was using around 400px wide as my standard for awhile but recently I'm using pics as large as 525px wide on 3-column (flexible) layouts. Like with choosing where the links in the posts point, affilates should be given a choice of photo sizes in the sponsor's rss feeds admin.
Many sponsors don't seem to know that most if not all blog designs are done with CSS in a "table-less" style. Some of our blogs are even coded to strict xhtml standards. So any extra code a sponsor puts into a post can really screw things up. They just need to give us the raw content so we can format and style it the way we want/need for each blog.
Posts in sponsor feeds should never contain any styling or formatting of any kind whatsoever. There should never be any code for tables, or blockquotes, or for borders, or alignment or color, and definitely no inline CSS styling code of any kind. No H1, H2 or H3 tags in the body of the post please. Also, there's no need for any extra break tags, particularly not between the closing of the image tag and the closing anchor tag. And many need to learn to use self-closing break tags.
As Walrus mentioned, sponsors need to stop linking a bunch of text in every post to their tour or gallery. Neither we nor our surfers need to be given half-a-dozen or more text links all pointing to the same place in every 200-word post.
Ideally a sponsor feed won't need to be touched at all and the posts can just be set to appear on a regular basis with no intervention by anyone needed. Feeds with posts which require editing are marked as 'pending' here and none of the posts are used until someone has time to go in and edit each post by hand -- which unfortunately means that sponsor's posts won't appear on our first pages as often as they could otherwise. Which translates to lower sales for those sponsors, so there really is a big benefit for the sponsors who get it right.
Besides, offering RSS feeds which are mostly unusable is just
