In recent years, there has been a lot of chaos in the second-hand housing market, and the relevant departments have also increased their efforts to crack down on it, effectively purifying the market environment. However, due to the complexity of the intermediate process of second-hand housing purchase and sale and the intermingled good and bad intermediary agencies, there are still many "pits" in the process of second-hand housing purchase and sale. Not long ago, the reporter spent two months in Beijing to check and select houses. After three intermediary changes and more than 100 house inspections, he finally signed a second-hand house sales contract and handled online signing. Reviewing the whole experience of buying a house is also a process of "avoiding pitfalls". It is difficult to distinguish the true from the false of housing source information. According to relevant statistics, in 2022, there will be nearly 20000 housing districts in stock in Beijing. Half of the housing stock is distributed in Chaoyang, Haidian, Xicheng and Fengtai districts. How to select the house you want in the massive second-hand housing market? For most buyers, online house selection is undoubtedly a more convenient way. The reporter found in the house selection that there are many websites and apps in the current market that can search the house listings according to the key words such as budget, age, location, whether there is an elevator, and whether there is "five unique". Some of these websites and apps are developed by intermediary agencies according to the house listings they represent, and some are the house listings information collected by third parties in the market. After determining the demand and budget, the reporter began to select houses online, but found many problems. For example, when using an intermediary app to search, we found that there are more than a dozen houses in a community that meet the requirements, but after careful identification, we found that these are actually the same house, but the recommenders are different. "Strange" is that after the reporter went to the intermediary for on-site consultation, he opened the collection folder and found that the original duplicate houses have disappeared. For the buyer, the ownership of the house use, whether it is "full of five unique", and whether it is a brick concrete structure or a steel concrete structure are particularly important. The use of houses such as apartments and commercial offices means that there are problems with property rights and settlement. The houses that are not "the only one in five" mean that more taxes should be paid. The steel concrete structure means that the loan life is longer and the loan amount is more. However, the reporter found that the most basic housing information was full of mistakes on some intermediary websites or apps. It is worth noting that due to historical reasons, some houses have not issued house property certificates, or the time on the house property certificates and land use certificates cannot reflect the real age of the house. In practice, this situation is generally determined by the housing evaluation agency, and the age of the house affects the life of the house loan. The reporter originally liked a house, but the intermediary has always said that it was built in 2000. It can use the combination of "provident fund+commercial loan" to lend for 25 years. The reporter was ready to buy it, but after checking the valuation of the house sold in the same building two months ago, it was found that the building was built in 1996. The intermediary immediately said that it would update the data on the app, and until the reporter bought a house in another community, the age of completion of the above houses displayed on the app did not change. When asking the intermediary online, the other party still said it was a house in 2000. Some intermediaries have low literacy. In the process of reporters' house viewing, many intermediaries often bring them together. At most, there are five intermediaries at a time. Generally speaking, room