[devs1010]

they have no direct influence unless they are a customer (paying money to Wikipedia), sure they can try to game the system, but Wikipedia isn't going to do some action at their request. If a company pays a lot of money to Wikipedia its possible someone within the Wiki organization would be willing to bend the rules a bit to cave to their request because it may keep the money flowing whereas otherwise tough decisions would have to be made (laying people off, etc)

[gojomo]

If Wikipedians are so trivially corruptible by money, ads are still irrelevant to the process. Just offer a donation for warmer treatment. (The Foundation does not reject corporate donations.) Or an outright bribe.

Also, the organization that handles funds – the Foundation – has very little special editorial power, and their actions are especially transparent. (For example, their real names are necessarily known, whiich is not the case for other editors.) Attempting to influence content by being an advertiser, then making ad spends conditional on favorable bias, would be about the worst possible way to try to influence Wikipedia content. You'd be spending a lot, via a path that's under the most scrutiny. You'd probably prompt staff to be extra harsh on you to avoid any appearance of infuence.

Anyone who really wanted to spend to influence Wikipedia would just hire editors outside the funds/ads-handling organization. That threat is larger, and unaffected by the presence or absence of advertising.