Credit card issuers have created all sorts of rewards cards which are now readily available in the market. Nearly all the cards offer cash back, while others lure consumers with the prospects of earning airline miles, or even collecting points. The way it works is that the points collected can be traded in for airline tickets, hotel stays, rental cars, cruises, gift cards or even merchandise.

But according to Consumer Reports, the ads make it seem so easy to earn a reward. In reality, it is alot more difficult. Amanda Walker, senior editor at Consumer Reports says: “You can get a small amount of what you spend back, but it can be very difficult.”  “There are lots of ‘gotchas’ with these cards.”

Consumers are also being advised to watch out for reward programs which are often said to be complex. There may be limits on what a card user can earn each month or during the year. Additionally, it is worth noting that rewards can expire which means no point will be earned on late payment.

Market analysts believe that credit card consumers may also have to spend a certain amount of money during the year to take full advantage of the savings. For instance, with the AmEx Blue Cash card (top-rated by Consumer Reports) offers a 5% rebate on purchases at supermarkets, gas stations and drug stores upon spending $6,500 or more. Spend less than that and the rebate drops to just 1%.

For consumers who find themselves caught up in the reward card craze, they can easily bust their monthly budget. Curtis Arnold of North Little Rock, Ark. pays with plastic and told MSNBC: “We use our card for literally everything,” he says. “Any purchase over $5 we put on our credit card and we do that is to maximize our rebate.

Arnold, who founded the website CardRatings.com, knows there’s a dark side to reward credit cards and has warned consumers to be careful with their spending: “Studies have shown that consumers do spend more on reward cards.” However, because consumers needs and budgets vary, rewards cards aren’t for everyone. They usually come with a higher interest rate, so they only make sense for people who pay off their balance in full each month.

Greg McBride, senior financial analyst at bankrate.com told MSNBC: “If you carry a balance even occasionally, forget about rewards cards,” That interest will more than wipe out any rewards you earn.”

In its July issue, Consumer Reports compared various types of rewards cards and concluded that cash-back cards are usually the most generous. Walker said: “You tend to get the highest percentage back for your spending and they’re the easiest to use.”

Consumer Reports says cards that deal in points are often a little less generous. Airline cards are the most confusing. They tend to change the rules more than other rewards programs. And as anyone who’s ever tried to get a free ticket with miles knows, they can be difficult to use.

And that will probably get worse. With airlines cutting flights, there will be fewer reward seats available. Consumers may soon have to pay a service fee to redeem those miles. Last week, U.S. Airways announced it will charge between $25 and $50 for all award tickets issued on or after August 6. Don’t be surprised if other airlines do the same.