Can you give an example? The only issue I've ever had with ABP et al. is when I'm working on a site and forget to turn it off & I think my site is broken (because ad doesn't load). :p

One of our webdevs complained about some issue that was causing issues with our site in particular (regarding generic id names being blocked) and since then I've had several anecdotal instances where disabling adblock on sites seems to clear up nagging issues.

I should have been more clear. My apologies.

Well it happens if you name your javascript ad*.js or similar, also should be extremely easy to find.

I haven't found a significant example of this, and I've been browsing with Adblock Plus for years. The only place I've seen issues with is some video streaming sites, when it interferes with streaming ads.