You ask for sources to help decide one way or another which is important since this is not a clear-cut situation.
The classical halachic case closest to this case that I can think of is the question of whether one can enter a shop to browse with no intention of buying (more precisely, knowing full well in advance one doesn't want to buy anything, e.g., to check prices).
It is an example of onaat devarim (hurting with words) and is forbidden (SA CM 228 based on Vayikra 25:17 lo tonu ish et amito and Baba Metzia 58b) to avoid disappointing the seller. It is of course fine to enter the shop, browse and leave if one didn't find something interesting, as long as there was a real possibility one could have bought something.
The rationale for the interdiction is not entirely defined. Halachipedia mentions that the Meiri gives two reasons for the prohibition: (1) other potential customers who observe one’s decision to refrain from purchasing the item would conclude that the item is overpriced and would consequently only buy it for less, causing the seller financial pain and (2) one’s decision to refrain from buying the item, having appeared to be interested, causes the seller to feel dejected.
R Meir Orlian mentions one is taking time from the seller that he could invest to serve other customers.
I think the analogy with clicking on contextual ads holds when building on the latter explanation. If one is sure one will not buy, then clicking is taking resources (money) away from the seller which he could have invested to sell to others. Advertisers will often buy a finite amount of ad impressions so one is taking away a finite resource knowing full well one will not buy. On the other side if there is a small but non nil chance one might buy then it is of course perfectly acceptable to click.
An important limitation of onaat devarim is that it applies primarily to Jews (Rama CM 228:1, one reason is that non-Jews don't have this sort of laws so we don't need to go beyond their law in our relations with them). This has very practical implications when clicking on ads from non-Jewish sellers and outside of Israel.
See here, here and there for relevant discussions of these sources. And please CYLOR if practically relevant.