As most of us know, a lot of what defines the paleo diet is what we aren't supposed to eat because they're supposedly bad for us. Of course, I think over time we discover that some things were just bogeymen, imaginary threats to our health designed more to control our behaviour than actually have positive results.
For example, I think saturated fat has proven to be a bogeyman. Loren Cordain's take was this was nearly as bad as other verboten foods/nutrients/factors, but that's largely been discounted as false.
I certainly have my own opinion on the matter (a lot of paleo recommendations are bogeymen), but I think it would be interesting to get others' take on the question. As an unrelated aside, there's a lot of interesting reading on bogeymen on Wikipedia - the history, the cultural differences/similarities, etc…
The problem is people want clear cut recommendations or lists of "approved" foods when they start out with Paleo because that is what they are used to when they start other "diets". Try telling someone who isn't familiar with Paleo that it's just a "template" and that you may or may not be able to eat nightshades or dairy or legumes or "safe starches" etc. all depending on your current health, your goals, perhaps your ancestry and numerous other factors. They don't get it, they're not sure what to do and they are less likely to be successful.
So, people find a list and stick with it. But, whatever "list" the follow is likely to prohibit some foods that actually don't cause them problems. Or they may cause a problem when they are overweight or metabolically deranged, but then are fine to eat once they are healthy. Or they may be fine in small amounts but problematic when eaten in significant quantities.
However, you may not know what foods cause you problems until you eliminate them and reintroduce them later in a systematic manner paying attention to how the food affects your body. Even that is not foolproof as some foods may have no outward short term negative consequences but may have long term negative consequences.
So, in my opinion, there are not many bogeyman recommendations. Rather, there are several foods that fall in a gray "it depends" area. If it turns out a specific food causes you no problems when you reintroduce it, that doesn't mean that recommendation to eliminate it was a bogeyman, rather it just means that you are lucky enough to tolerate that food.
Having said all that, fear of saturated fat is a bogeyman. :)
for me I would add Peas, Green Beans, and Peanuts.
When I started everyone told me to say no to legumes, all legumes, all the time... that included the three above. I reintroduced them to my diet, and I have seen no negative effects.
Yes peanuts contain phytic acid, but less so than almonds and walnuts. Yes peanuts have high aflatoxins, but roasting, and especially grinding (i.e. peanut butter) removes most of that. They are cheap, tasty, and when I am hungry a spoonful of peanut butter really satisfies me much more so than almond butter or sun butter.
Peas and Green Beans are TASTY, have a glycemic load of 1 and 4 respectively, contain lectins that most humans process without trouble...
The blanket no legumes is a bogeyman