I understand the problem and I believe most publishers have the same issue. But blocking networks isn't smart because it lowers the pressure in auctions. Less buyers (weither it's CPC or CPM) means lower resultst in auctions so overall less earnings.

Is there a way to force ad networks to compete for ad space

Uhm... No. Forcing a party to compete is not how an auction works. Buyers freely participate, the more buyers you can attract the higher the price will be.

Your observation are correct about CPC vs CPM, but your reasoning has lead you astray. The AdSense auction is structured such that the ad with the highest likelihood of earning you the most money wins, irrespective of the bid type (CPM, CPC, and others). Typically if a buyer is in the auction and has CPC ad that is of high quality (ie high likelyhood of being clicked) that ad will win over any CPC bids. The flaw in your reasoning is that there isn't sufficient demand from high paying CPC ads to fill all the inventory (your impressions). It would be nice if that were the case but it isn't. Basically by blocking CPM ads, what you are doing is taking the high paying ads and then telling the CPM bidders "sorry keep your money, I rather receive 0$ instead of the low rates that you pay". Essentially your are taking no-money instead of some-money.

But there is an even bigger impact of this action, because the CPM bidders participate in all the auctions for your inventory, so by blocking them you are reducing the demand for a fixed supply. The result is lower prices across the board, even the CPC ads end up being lower paid. (This is what Runfun pointed out above).

What's the solution? From a pure profit perspective there is no real justification for blocking CPM ads, but in a the real world these ads tend to be of lower quality and often look spammy. This also applies to low priced CPC ads. So eliminating these ads, tends to have little real impact on earnings but showing them does come at a cost. That is, they look bad and reflect badly on your website and brand. There is justification for blocking them. The best solution I have found is to use the ad-balancer feature. This will dynamically remove the lowest paying ads from your inventory. So if an ad doesn't pay enough, no ad is shown. You reduce demand by blocking the low paying ad, but at the same time you eliminate the supply from the inventory. This will holds prices up. This doesn't discriminate based on bid type. I doubt that you really care what the bid type, provided that you are sure that your are being paid the best price possible for you inventory. This feature achieves that.

The only other solution is to somehow promote your website in an attempt to increase demand among potential advertisers.

Good luck.

I'd like to allow ad networks but only if I can make CPM bids unavailable, is that possible?

I fully understand the effect on CPC value if I avoid CPM ads but my total earnings are still (much) better without CPM ads. YMMV based on CTR.

I HATE CPM ads. It is free real estate for those cheapskates that don't want to pay anything. It takes about 3 impressions to get 1 penny.
Years ago, Google allowed me to "opt out" of CPM ads, which I did. Then, they changed the rules, and "re-opted me in". I strongly disapprove.
They felt they needed to force us to be slaves, for the sake of their ever-increasing profits.

I allow JUST ONE network - Adsense. I believe that the "ad pressure" argument is BullSpit. I don't want the riff-raff.
If you are not good enough for AdSense, why would I want your inferior ads, to degrade my website?
I am VERY aggressive with the ad balance feature. It STILL allows the sub-penny ads, which I think is also BS!
Remember the argument to allow webmasters to set a minimum $ click? THAT didn't go anywhere, and never will.
If they were able to serve sub-$0.00001 ads, I think they would. Only then, would webmasters scream.

If I could deny ALL CPM ads once again, I would be all over it. But the deck is stacked against the webmaster, in favor of the ad buyers - even the cheapskates ... ESPECIALLY the cheapskates.
Today, Google demands every hint of any revenue whatsoever, to the chagrin of many webmasters. Like me.
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[edited by: Sally_Stitts at 7:44 pm (utc) on Jan 30, 2019]

It is very easy to deny CPM ads. Block all third party networks. AdWords only offers CPC and, AV-CPM. AV-CPM is Active View CPM, which means that one only gets paid if the ad is actually viewed. This tends to pay much better than standard CPM but it only accounts for a small percentage of the total impressions (at least in my case. I'm at <3% of total impressions).

Now if you are pushing the ad-balancer aggressively and still seeing low quality ads then your real issue isn't the bid type but a lack of interest on the part of advertisers.

That's just fine. I don't want their interest.

Every day, I get pages with 1 cent earnings. Unlike Google, I would rather have ZERO earnings from these pages, than be a doormat for cheapskates, and degrade the user experience of my visitors.

I agree that the % is low. But I would still like to see it lower. As in, non-existent.
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Why all the anger and the bitterness?

One has a website that covers some niche topic. Business that serve that niche have a genuine interest in connecting with people interested in that niche. Thus they buy ad space on the website. There is nothing about being a "doormat" in that. If one has website about cars and there isn't a single ad from any car companies then that raises some flags about quality and trust.

This has changed somewhat with personalized ads, but contextual ads should still account for a good portion of the overall impressions.

Anger and bitterness? That's a bit over the top.
For simply expressing my strong, long-held views?

The fact is I am a pretty happy camper this month, because AdSense has started to treat me really well once again.
My "bad/ not-so-bad" bit has definitely been flipped to "not-so-bad". Which is very encouraging. Maybe there is life after death. I'm guessing that constant diligence is a factor, if noticed, and taken into account.
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