People who try and find errors and then demand a cheaper price. I've had this happen twice and I wanted to scream.
People that can't keep appointments or show up on time. It is the ultimate display of selfishness, self centeredness and a general attitude of "your time is worth sh** to me". I am cutting off a few potential clients this morning, actually issuing e-mail ultimatums (in a very sweet way) to let them know they either figure out a date that DOES work for them, so we can meet, get a deposit on the books, etc., etc., or I will wash my hands of them entirely. No amount of money in the world is worth holding on to PITA's, and the ones that are showing signs of possibly being PITAS.
And finally making it by on Monday evening to pick up samples from a planned tasting event the Saturday before...not cool. I definitely hope I never hear from this piece of work again. But being a good business gal that I am, attempted to contact her and ask her how her samples were and if I could be of any further assistance. So, that's my last email ever. 
[Since I share the gray hair with them, it's easy for me to kinda laugh and say, "Yeah, nothing like when you and I got married, huh?"
One of my favorite stories is when my Mother-in-Law was complaining how she and FIL went to dinner and it cost them
FIFTEEN DOLLARS! I went out to dinner Tuesday night and left a tip bigger than that! God luv 'em!
That is so funny,as I said when I see an elderly,I'm weak and can't say no, reminds me of my granny,she died over 10 years ago and I miss her so much.
Oh, I have another one! When people call me and say "I'm on your website now, but I have a few questions":
(them)...where are you located?
(me)...if you look on my website, the map is right there.
(them)...what flavors of cake/filling do you have?
(me)...if you look on my website, the flavors are listed .
(them)...do you have any photos of your work?
(me)...if you look on my website, my galleries are all there.
You get the idea...! 
Oh, and by the way, YELLOW IS NOT A CAKE FLAVOR!!! IT'S A COLOR!!!<S>
LOL ~ that is funny!
I really dislike when people are late to pick up their cake.....like I have nothing better to do than wait around for them....oh yeah and short notice orders drive me batty!
You want it when? o_O
I once did a cake for a friend who was giving a baby shower and after I delivered it she said she was going to start decorating cakes so she could do her 2 kids birthday cakes and save that $35.00 she normally spends on them.
I wanted to say:
1. $35.00 is a bargain no matter where you go!
2. You would spend more to buy all the equipment!
And the third thing I wanted to say...
"CHEAPSKATE!!"
I really dislike when people are late to pick up their cake.....like I have nothing better to do than wait around for them....
A good way to battle this .... once in a blue moon, I'll have a cake pickup on a day I have a wedding catering (I try to avoid those, but .....). I tell them, "You will need to pick it up by 2:00. I am locking the door and leaving at 2:10, so if you're not there before then, you won't have a cake." I also explain that I'm LEAVING at 2:10, so if they get there at 2:09, I will NOT have time for their transaction, so they would probably do better to plan to get there before 1:30.
They are usually there 30-60 minutes PRIOR! Warn them "I'm leaving so you'll have no cake" and they'll get there! 
That's what I used to do, too, before I had my shop.
I would thell THEM when they could pick up the cake.
"You can pick up the cake between 10 am and 12 noon."
It drives me crazy when people clearly KNOW exactly what they want, but they want you to be a mind reader.
them: so what do you think would look good on the bottom tier
me: I was thinking maybe some swiss dots
them: oh I was thinking about stripes
me: okay, vertical stripes?
them: no I was thinking horizontal
me: oh okay, *sketching* how about like this
them: no, I want 3 perfectly spaced parallel horizontal stripes.
why even ask what I think if you know what you want?!
I also get really annoyed by vague emails, I just got one the other day. My fiance and I are thinking about getting married in March 2010. Can you call me with information? That's more than just information...
How about the emails that start with, "Can you send me any pictures of a [insert Thomas the Train, Elmo, some other common kids theme] cake you have done?" These, I can understand since they are pretty popular. But I get some off the wall stuff. "Can you send me a picture of any Alf cakes you have done?"
Oh, new one! Not too new, but just reminded. I just got an email from a JUNE 13th bride asking me how her cake is coming along?!?! Not the first time I have had such a weird email. uh... your cake is doing... nothing right now... because it's not due for 7 weeks!!!!
How about the emails that start with, "Can you send me any pictures of a [insert Thomas the Train, Elmo, some other common kids theme] cake you have done?" These, I can understand since they are pretty popular. But I get some off the wall stuff. "Can you send me a picture of any Alf cakes you have done?"
What? You haven't done a 13 variety slideshow of Alf cakes? Surely you can get some dummy cakes and practice Alf cakes so you'll have lots of pictures to show her.
Hilarious! 
I have actually had customers call and order lets say a birthday cake and I'll ask how do you want it decorated and I get "I don't care" do anything you want. HUH! Well I need some idea. Again I get whatever you want to do is fine. That drives me nuts. I can't wait for the first time I do a teddy bear cake for a eldery lady because no one told me what to do or her age.
I have enough gray hair!!!!!!!!!
.... and I'll ask how do you want it decorated and I get "I don't care" do anything you want.
And thus was coined my phrase, "Oh good! That means I get to decide and you dont' get to complain!" That usually lights a fire under 'em.
Mine is really when people don't show up and/or are several hours late picking up their orders. I am very punctual, so that one drive me craaaazy!
This drives me nuts!! Yes, I AM running a business, BUT I am Not running a daycare. I do not have time to baby sit their cake. Why do these people think I set a time for pick up? Just so I know when to start waiting!!
I had a doosey just recently and it still bugs me to this day.
them: I was calling about your cakes.
me: Yes, how can I help you?
them: how much is it for a big cake?
me: how big is big?
them: I just wanted a really big cake
me: is it going to serve 50 or 100 people?
them: I don't know
I was like 
and 
because I got nowhere with this call and wasted my breath for about 5min.
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