For sure, I understand that this makes the data less scientifically valid, but I try to follow some kind of process for Agreeing other users’ identifications of my observations.
Firstly, what do I know of the identifier’s expertise? I’m not going to doubt a beetle identification by borisb, for example.
Then, what was my original impression? I also realise this is not always watertight, but I try to do some research into species I am unfamiliar with to get some idea, but then leave my own identification for the observation at “Class”, “Order” or “Family” level if I have no real knowledge to back this up!
Next, I (almost) always take a look on-line to see how the new identification compares with information available from web resources. Often, I have no idea how close one species may be to another nor how to differentiate them, but I’ll Agree anyway if it looks right!
I think for new users it’s very difficult to know if other users’ identifications are accurate, and the desire to learn new species and find out what one has seen can override scientific integrity, but this also leads to new learning, and corrections are always there to be made.
On the other hand, I also agree that any scientific use of the data should require extra validation by the scientist, depending on the context. Observations of Eurasian Magpie, for example, can surely be taken at face value without too much scrutiny, whereas observations of Grey Dagger moths should be taken more cautiously.