Flipping is 100% cool with me; I do it all the time. Just don't lie to another collector to get a deal. Have some respect for your fellow community members or you will quickly find yourself with a rep for being a jerk and on the outs with many potential deal participants.
Good name in man and woman, dear my lord,
Is the immediate jewel of their souls:
Who steals my purse steals trash; 'tis something, nothing;
'Twas mine, 'tis his, and has been slave to thousands;
But he that filches from me my good name
Robs me of that which not enriches him
And makes me poor indeed.
--William Shakespeare, "Othello", Act 3 scene 3