I think it is unsportsmanlike and even rude. When I was a teen I had an IM as coach. He told us as advice: "never offer draw in a worse position". And there is a logic to it. If the opponent evaluates correctly the position, he will refuse. Now, in OTB chess it is not only impolite, but against the rules to offer draw several times in a row. The opponent can report You to the arbiter. And You will get a warning. If You repeat it, You might lose by arbitration forfeit as a penalty.
One should offer draw when (s)he equalised or is slightly better. The likelihood that the opponent will accept is much higher. But there is a psychological aspect, too: opponents, who were in a better position might fail to realise that You equalised, and reject the offer. But, this is the moment when You start to play for a win. This happened me twice on this site with a Czech opponent:
Playing White, I was slightly better. He misevaluated the position and rejected my offer made at the beginning of a somewhat better R + N vs R + N endgame (equal number of pawns, I had a passed pawn, but no big deal). He missed a tactic, I won a pawn and the game.
Playing Black, I also was slightly better. But with Q + B of the same colour on the board, a defended passer seemed to matter less. He offered draw, I think, three time in a row, but I remembered two principles: (1) in endgames with (opposite coloured) Bishops You attack on the colour of Your Bishop; (2) when You have Bishop and Queen, You put the Queen on the opposite colour to control squares of both colour. Capitalising on a mistake and apllying these principles I Czech, sorry, check-mated him. 
It is a bit OFF TOPIC. Sorry!
ask for a draw in a lost position
If only people behaved in real life they way they do on the internet.
Note that I did not make the statement the other way around, as people usually do.
Sometimes it may be possible to pull it off. Once my opponent offered a draw a few times and I refused because I felt I was slightly better. But then I made a few mistakes, and although material was even, I believed I was worse (and, checking after the game with a computer, I was about -3 as white, so I judged correctly). And then, he took my draw offer!
But if the position is clearly balanced toward one side, then it's rude to offer a draw.
mrs polgar asked susan when she was very young when she got beat beat by a stronger player if she offered a draw...susan said yes...her mother said good girl
It's because there's a tiny chance the opponent will accept the draw. I see the same thing in Fantasy Football, where people offer to trade very bad players for a star player of mine. I ask them why they'd insult my intelligence with such an offer and they reply that you never know when someone evaluates wrong. The same with chess.
it may give you a small chance of a draw rather than loss, if your opponent accepted it. But I agree; it's poor sportsmanship to offer a draw if you're clearly lost. It bugs me every time someone does it to me, so I wouldn't do it to others. I might win one more game every 100 doing this kind of thing, but then I have to live with myself being a jerk.
Why some people do that?
Maybe they tried to click on resign but click on wrong icon?
If you are lost, you can continue and wait for an opponent's mistake or you can resign, but ask for draw is silly.