is it good or bad to have a cheat day?

I agree with some others who say a whole day of cheating can completely derail you. In one day you can undo the calorie deficit you've worked so hard for all week. I let myself have one cheat MEAL a week, and always out at a restaurant, I don't like to bring cheat foods into the house - too dangerous for me! Then I can look forward all week to knowing that I will allow myself pasta or a burger on Friday and not feel an ounce of guilt about it because I ate healthy and worked out all week. Then I leave the restaurant behind, and once at home, it's right back on track. Increasing your calories a little one day of the week also keeps your metabolism from going into starvation mode, where your body will desperately hold on to fat. Good luck!!

My trainer suggests one meal, instead of entire day, also make sure you log it, it really helps you stay on track. also, you need a rest day on exercise. i know it can be hard to take a break, myself i let myself do a walk instead of a run and call it a rest day if you feel tired or run down, you have to listen to your body.
sometimes if i let myself cheat too much i end up just trashing my efforts, so logging the meals or even just snapping a picture with the camera phone, helps me stay on track. this time of year is especially hard.

It's all about whether or not you can handle it. Personally I like cheat days-- they keep me on track and I don't feel deprived. But I don't cheat by thousands of calories; I'll just have one meal out where I don't worry about what I order. Or if I'm really cravings something and I've been really good the past few days, I'll indulge and not feel guilty. I don't have them often-- just on special occasions or every couple of weeks. If, however, one cheat leads to a downward spiral of cheating then it might be better not to. I know a lot of people just work the things they would normally "cheat" with into their daily goal so it's not really cheating. Like they plan 100 cals at the end of the day for a little bit of dark chocolate.

The bottom line is to figure out what works for you and do that.

Today is my cheat day its my break from exercising and I can eat foods I don't normally eat.. but not too much.

Is it good to have a cheat day or not?

I think it's good, or it sure is for me.
My results speak for itself, so there is no question in my mind.

I think there is a psychological and physiological advantage. A good pig out shocks the metabolism and also allows me to spurge on the foods I crave. Again, the proof is in the results, and I would not live any other way.

Free Days - YES!

I do what some people would call 'cheating' every single day... only I call it 'eating in moderation'. :-)

Since joining MFP in April, not a single day has gone by that I have not had pizza or a cupcake or a cheeseburger or cookies or french fries - or some other food labeled 'bad' or 'a treat'. I just watch my portion sizes and total calories.

It's worked really well for me! I've lost 45 pounds and am just seven pounds from my ultimate goal weight.

I do sometimes but i do the above mainly. I eat snacks that I like so I don't have to have a huge blowout every week. No way I am giving up things that I want. Have lost over 110 pounds this way and I am relatively fit, so i don't see why I should change..

I believe everyone deserves a day to eat a little extra & not work out. Especially a break from working out so your body can rest. [:
I'm gonna start doing it once a week, for one meal. But nothing too bad.

agreed. Its not good or bad, what it is is NORMAL!

Oh and if you're having to "cheat" then you clearly have not mastered the point of a balanced diet and the mentality of moderation, which is the only thing that will keep the weight off and you healthy.

Meh. I used to have a designated "Cheat day" (Sundays) in which I would allow myself not to exercise, and I'd eat whatever quantities I wanted (I only ever ever eat healthy foods though - so it was much larger quantities of beans, oatmeal, salads, etc all day - but still not netting more than 1500 cals or so), and it would take me about a week to get that [water/food] weight off, so I found it wasn't worth it for me.

Oh and if you're having to "cheat" then you clearly have not mastered the point of a balanced diet and the mentality of moderation, which is the only thing that will keep the weight off and you healthy.

Really??? Sorry will have to disagree, i am 11 lbs. away from losing 300 lbs. in 29 months and if I haven't figured it out by now than god help me.... lol The word cheat in this context simply means eat outside of the norm. I log 50-70 miles a week at the gym and put in 3 days of weight training, I prefer to stick to a meal plan of chicken, fish, and lean beef as well as whole grains and veggies that makes up the bulk of my week. So when I say I am having a cheat meal (Pizza Hut, BW3, Mexican, etc) to me it is a cheat meal from my normal routine, it certainly doesn't mean I don't know how to eat in moderation or that I haven't mastered my lifestyle......... Just my 2 cents....... :-)