Of course you can spot them with the 1st message.  I only use WhatsApp with SB's that ask me to use the app, so any unsolicited message I get is scammy.    

 
I like to answer the first few messages as though I am the intended recipient.  I never claim to be the named person, I just give answers that are a reasonable-looking reply.  

 
Scammer: "Dan, did you have time to review the quotes for the project?"  
Me: "I did!  I think they need a lot of work before presentation. Frankly I'm pretty disappointed in you."  

 
Whatever the reply I just go with it and keep moving the conversation along.  Great fun!  When the scammer finally decides to set the crypto trap, I shut them down with one simple sentence:  

 
Me:  "I don't believe in trading commodities, especially those based on fantasy valuations."

 
That usually brings silence.

 
Other tactics: I go deep into romance mode.  Asking for pics, then more pics after I proclaim "her" beauty. Then I ask questions about her life, parents, past sexual experiences and promises to "rock here world" when we finally get together.  Throughout all of this I repeatedly ask her to meet me for dinner. I explain that a face to face date is critical to build trust and affection.  Ultimately, I offer to send her my "best dick pic" with the promise she won't share it with anyone, because that would ruin me.  After I get her to promise multiple times, I send her a pic of Trump.  

 
Eventually they realize I am a colossal time-waster.  Mission accomplished.  

 
Life is good

 
The Cat