I have done two purchases so far this year with a credit card. I bought 1 for $50K(the property was worth almost $90K in its current condition) and then refinanced it $70K and paid off the card and used the additional cash to complete the rehab and then sold it in 6 weeks for $142K. The second deal had similiar numbers.
Best part about it was I used the credit card companies money free for the first 25 days and then paid off the mortgage before a single payment was due!
If you have a card with a high enough limit(or two+ cards) especially if you have convience checks it can work but you should be careful and had better have your exit strategy already figured out befor you do it.
Keep in mind that it is against the law to borrow money to borrow money.