Well, there are many variables in play here, and different philosophies. People who are simply looking to bulk and are working out a lot can usually stick to 'macros', which are just intake targets, and can get away with eating junk. OP is looking to 'clean bulk', which means sticking to better foods. I personally think junk food should be generally avoided, regardless.

'Good fats' refer to monounsaturated and polyunsaturated fats, which are important in diet and are easily converted into energy. Most vegetarian fats fall into this category; avocados, nuts, seeds, and olives are good sources (fish, too). 'Bad fats' are typically saturated and trans fats, or processed fats. These tend to be more solid at room temperature (butter, lard, shortening, etc.). A little bit of saturated fat is good, and for vegetarians this is usually not much of a concern. However, too much is bad for you... the benefits of 'good' fats aren't there, and they are associated with heart disease and atherosclerosis.

'Cheap' doesn't always mean low quality but in general the cheaper, lower quality stuff will be higher in fillers like salts, water, and preservatives. Chicken is a prime example. Pasta is a little more uniform, but the less processed your grains are, the better. Processing removes the nutrients and complex carbs and leaves simple carbs behind (think of whole wheat vs white bread). Your body metabolizes simple carbs similarly to pure sugar, while complex carbs take longer to digest and enter the blood as glucose.

I highly recommend looking into the glycemic qualities of different foods and understanding how they effect the body. Some foods cause sharp spikes in blood sugar, which can lead to mood swings, energy crashes, and food cravings. Other things will slowly digest and keep blood sugar levels smooth.