Well, ask for the screenshot.

STΕAM VERΙFΙCATION SUPPORΤ :

Dear Steam-user

Steam Verification Support has detected multiple ip usage on this account.
Your account is in danger of beeing banned by Steam. Rules § 13 on steampowered.com says, that it is not allowed to share or trade an account.
Please type here your username and your password to prove that only YOU use this account, this is for your own safety! (Please format the information as USERNAME/PASSWORD, all CAPITAL). Thank you. For questions visit steampowered.com
[SpA]Saint K.: YOURMOTHER/HASAIDS
STΕAM VERΙFΙCATION SUPPORΤ :

Please format the information as USERNAME/PASSWORD, all CAPITAL. Thank you

(ATTENTION: WRONG INFORMATION!, retries left: 3)
[SpA]Saint K.: YOURMOTHER/HASCANCER?
STΕAM VERΙFΙCATION SUPPORΤ :

Please format the information as USERNAME/PASSWORD, all CAPITAL. Thank you

(ATTENTION: WRONG INFORMATION!, retries left: 2)
[SpA]Saint K.: YOURDAD/HASAIDS
[SpA]Saint K.: did i win yet?
[SpA]Saint K.: hello?
[SpA]Saint K.: i want my price

Bad spelling usually means that the scammers are of young age and/or retarded.