When you design a PPC ad for Google, Bing, or YouTube, what page do you send people to who click the ad? If you're like most apartment marketers (and most PPC users generally), you don't use a landing page tied to that ad's content; you simply send them to your home page.
In fact, according to Unbounce 80% of PPC ads do not send users to specific landing pages. And as Unbounce puts it, "If your PPC campaigns are not using landing pages, then your highest converting call-to-action is likely to be the back button on your visitors browser – which means marketing dollars going to waste." This is a classic mistake made when marketing apartments on AdWords--or marketing anywhere else, in fact.
Think about it this way: When people search on Google and end up on your site, they aren't looking for you. They don't care about you. They care about themselves and they're on Google because they have a problem they want to solve. And they clicked your ad because they thought you might be able to solve their problem.
But when they pulled up the website and found a home page with two dozen options, none of which seemed to immediately pertain to their problem... you lost them. They clicked the back button and went back to Google because they knew they couldn't find their solution on your site and they might be able to on Google.
The funny thing about this is that Google's own training videos tell AdWords users to send visitors to a specific page instead of the generic company home page. But it seems that Google's users don't look at Google's own training videos. Google doesn't mind... they'll take your money for every click, even if the user immediately bounces. They figure that they did their job and got someone to your site. What happens from there is up to you and if they immediately bounce... well, it isn't their fault.
How do you design effective ads, then? Well, target your ads for specific products--don't just aim at "apartments in (city)." That search term is so broad that you'll get plenty of bad clicks that cost you money plus even showing up on the main page will require a shoot-the-moon type bid. Instead, target "one bedroom apartments near the airport in (city)" or something like that. It's a narrower key word so the clicks you get are almost certainly going to be warmer leads. And when you design the ad, set it up so that the user can easily get to your one bedroom floorplan. You can either send them directly to the one-bedroom floorplan page with the ad or you can make it a site link that is easy to navigate to out of the ad or on the landing page.
When you fail to do this and instead target broad keywords and use bad landing pages, you end up wasting money on AdWords and missing out on what can be a phenomenally effective (and affordable!) advertising platform.