It can be both easy and hard to spot a fake ad. There are some typical 'danger signs' which makes a fake ad easy to spot, but scammers are getting better and therefore some ads can be harder to spot.
On findroommate we go through all ads when they are created to make sure no scammers are allowed to the site. Most housing sites have this process but on social media such as Facebook there's much less control with the ads being posted and it is therefore easier for scammers to get in touch with home seekers.
No matter where you are looking for accommodation, you should always pay attention to how real the ad and landlord seem. Are you in doubt, don't hesitate to contact the customer support for assistance.
Here are the typical signs of a fake ad:
The landlord tells you s/he has moved to another country
It is not possible to arrange a viewing of the place
The landlord can explain a lot about the surroundings of the apartment, but not tell much about the place itself. It is easy for a scammer to google some address and see what is placed close by.
The landlord uses pictures for the ad that looks very polished and could resemble a hotel room or a room in another country. For example a picture showing air condition in the room or palmes outside the window is in Denmark very unlikely as almost no homes have air condition and palmes are not very common.
The landlord asks for the deposit paid in cash or via a foreign service such as Western Union. (Paying in this way your payment can't be traced and can't be pulled back)
Does the ad seem to good to be true, it probably is. If you find an ad for an apartment in central Copenhagen for 4.000 DKK it is most likely fake as rent for an apartment in Copenhagen usually is much higher.
The list above shows the typical signs of a fake ad. The more intelligent scammers are harder to spot based on the ad itself. Then more thorough work must be done. Are you for example out viewing the place, take a look at the name tag on the door or door bell. Is the name on the door the same as the landlord your are in contact with? Is it not, see if you can find the contact information on the person whose name is on the door, and ask if the ad is real and the place truly is for rent.
Here's some good advice on how to avoid being scammed:
Don't ever transfer money to a foreign bank account or pay in cash
Make always sure to get a signed contract before you pay for the deposit
Has the landlord mentioned that the place previously has been rented, get the contact information to the previous tenants and ask them about the landlord and the sincerity of the ad
Make sure to always have seen the place before you pay the deposit
Make sure you always have met the landlord face to face. If not possible, at least have seen and talked to each other on skype or such
Make a Google search on some of the pictures posted on the ad. Is the picture used on other sites, make sure the ad is the same and the landlord is the same
Generally, you should use your own common sense. If your gut feeling tells you it is not right, don't sign the contract and don't pay any money to the landlord