In other words, subtlety of the dating ritual has been lost, you are being checked out from the moment you enter the room.
Another issue that crops up with dating and Thirty Somethings is the age group we should date. In our thirties the people we may meet could already have a child or be separated or divorced and don't want another child. If you are a woman you may be looking for a man who will make a good father. It is possible you will feel you don't have much in common with someone aged 21 but do find them attractive, on the other hand you may find yourself drawn to the more mature aspects of an older man or woman.
The next issue to hit Thirty Somethings when dating is where to date.
In your twenties you were are trance and rave clubs until 3am, or in bars with friends dancing until all hours and still able to be fresh in the office for 8.30am.
You are tired of meeting jerks and timewasters and people who simply don't match with you, people out for sex and anything they can get.