Obviously we don't believe it was satan. 
 
Better scriptural references are: 
 
- Acts 9:3-7 - Jesus appears to Saul/Paul 
- Acts 7:55-56 - Stephen sees God and Jesus Christ 
- Genesis 18:1 - The Lord appears to Abraham 
- Genesis 32:1-2,30 - Angels appear to Jacob 
- Genesis 48:3 - God appears to Jacob 
- Exodus 3:1-6 - Angel of Lord appears to Moses 
- Many, many at time of Jesus birth 
- etc. 
 
The Bible is full of references of God appearing to man or his angels appearing to man. If it could happen in the Old and New Testaments (before and after Jesus came to earth) - why can't it happen in our day? 
 
Hope this helps. 
 
Thanks

"And no marvel; for Satan himself is transformed into an angel of light."  
 
We all know that Satan is a Angel fallen from glory this is why his deceptions can be so appealing he himself can make evil look like good.  
 
Of, course we all must be weary of claims of visitations from the Lord or Angels because we know that Lucifer can manifest in such a form, though the scriptures tell us that when you see true Angels of the Lord it is easy to spot how lack luster Lucifer is now. (See Moses 1:13)  
 
2 Corinthians 11:14 is an important warning against deception. It is not a test of a true prophet though by any means. To simply believe that a prophet is fake because he claims to of been visited by and Angel or the Lord himself means you believe that Abraham, Issac, all the Apostles, Mary, and the majority of the prophets and people of the Biblical record are fakes cause many Angels were seen throughout the ministry of Christ.  
 
If you believe that Angels appeared to men then why would the Lord stop sending his messengers to his children to day?  
 
Do you believe that God is a respecter of persons? (See Acts 10:34) 
 
I think you are confusing a warning are assuming that warning is a test for a true prophet. Which it is not, now we do have several tests for prophets recorded in the old and new testaments.  
 
The best test I believe is the one that Christ himself told us in Matthew 7:15-16, "Beware of false prophets, which come to you in sheep’s clothing, but inwardly they are ravening wolves.Ye shall know them by their fruits." 
 
Christ tells us to test prophets by there fruits if they bring good fruits they are true prophets, if they bring bad fruits they are false prophets. To test the  
'fruits" of Joseph Smith I invite you to study, ponder, and pray about the Book of Mormon. The sacred text that Smith translated from an unknown and lost language into English through the power of God.  
 
If this translation is the word of God then it is a good fruit and Joseph is the prophet that he professed he was. The only way to know this is through prayer and the power of the Holy Ghost.