Hi John & Marg & welcome to the forum.
As the saying goes "You can't please all of the people all of the time" and i am sure you will find that it is the minority of people that whinge and moan about Calis. Most of the members on this forum would give their right arm to be able to move here permanently, but for most at the moment, that is not possible.
The beach was very busy last week, if it was that dirty and dangerous would people use it?
A month or so ago i was reading that many UK beaches are falling behind the guidlines for cleanliness, whatever beach you go on anywere in the world, it is always advisable to wear some sort of footwear.
Bars & restaurants always have menu's a price lists available, you can always look at the prices or ask for them, if you feel it is expensive don't stay. You will always find that beach front bars and restaurants are slightly higher priced (again this applies anywhere you go), search out the places that are set back from the front, you can get terrific meals at good prices.
If Calis is that bad, consider this, would that many of the members return year after year (in some cases 2, 3 or 4 times) and would they really be that inclined to buy property here.
Keep an open mind, don't let what you read from the minority put you off having a really enjoyable and unforgetable holiday.