First of all, disregard what your friends have been telling you, as they are completely wrong! What dental school did they go to?Cleaning your teeth will make your gums and bone supporting your teeth healthier, as right now you have gingivitis, and if not treated you will find that your gum infection will progressively get worse...and then you will find out about loose teeth that you have caused based on your neglect. Get them cleaned on a regular basis and floss daily and brush your teeth at least three times a day for at least 2-3 minutes each time.Regarding the yellow browns spots, they may be a permanent discoloration that possibly could be improved by professional teeth bleaching (i.e. having your dentist do the bleaching, NOT getting over the counter bleaching products), or they might be treated with direct composite fillings or even porcelain veneers.